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Database Download Record Fetch Fails in MacOS 15.2
A program I wrote in Swift that uploads and downloads to a private database in iCloud is failing for downloads since the the 15.2 update. It still works for uploads. I.e., I can download uploads made from the program under 15.2 on another computer running the same program under 15.1 The Fetch operation does not return an error, but the returnRecord is empty! I do get the error below after the fact of the failure, don't know if it's related. "ViewBridge to RemoteViewService Terminated: Error Domain=com.apple.ViewBridge Code=18 "(null)" UserInfo={com.apple.ViewBridge.error.hint=this process disconnected remote view controller -- benign unless unexpected, com.apple.ViewBridge.error.description=NSViewBridgeErrorCanceled}" To be clear, I assume I do have access to the database since it works for upload under 15.2, as well as upload and download under 15.1, and from a very similar program on my iPhone (which I haven't updated yet!) Questions? Comments? Thanks!
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Dec ’24
Ambiguous use of 'textField' in Xcode 26
func textField( _ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String ) -> Bool { if let delegate = delegate, let shouldChangeCharactersIn = delegate.textField { return shouldChangeCharactersIn(textField, range, string) } return true } This is from an extension extension TextInput: UITextFieldDelegate, ObservableTextFieldDelegateProtocol { The delegate is already a UITextFieldDelegate, but when you click on the error, it returns 7 instances of: "Found this candidate in module 'UIKit' (UIKit.UITextFieldDelegate.textField)" This doesn't give an error in Xcode 16. Is this an Xcode 26 bug?
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147
Jun ’25
The Peril of the Ampersand
A few years ago [1] Xcode added new warnings that help detect a nasty gotcha related to the lifetime of unsafe pointers. For example: Initialization of 'UnsafeMutablePointer<timeval>' results in a dangling pointer Inout expression creates a temporary pointer, but argument 'iov_base' should be a pointer that outlives the call to 'init(iov_base:iov_len:)' I’ve seen a lot of folks confused by these warnings, and by the lifetime of unsafe pointers in general, and this post is my attempt to clarify the topic. If you have questions about any of this, please put them in a new thread in the Programming Languages > Swift topic. Finally, I encourage you to watch the following WWDC presentations: WWDC 2020 Session 10648 Unsafe Swift WWDC 2020 Session 10167 Safely manage pointers in Swift These cover some of the same ground I’ve covered here, and a lot of other cool stuff as well. Share and Enjoy — Quinn “The Eskimo!” Apple Developer Relations, Developer Technical Support, Core OS/Hardware let myEmail = "eskimo" + "1" + "@apple.com" [1] Swift 5.2.2, as shipped in Xcode 11.4. See the discussion of SR-2790 in Xcode 11.4 Release Notes. Basics In Swift, the ampersand (&) indicates that a parameter is being passed inout. Consider this example: func addVarnish(_ product: inout String) { product += " varnish" } var waffle = "waffle" addVarnish(&waffle) // line A print(waffle) // printed: waffle varnish On line A, the ampersand tells you that waffle could be modified by addVarnish(_:). However, there is another use of ampersand that was designed to help with C interoperability. Consider this code: var tv = timeval() gettimeofday(&tv, nil) print(tv) // printed: timeval(tv_sec: 1590743104, tv_usec: 77027) The first parameter to gettimeofday is an UnsafeMutablePointer<timeval>. Here the ampersand denotes a conversion from a timeval to an UnsafeMutablePointer<timeval>. This conversion makes it much easier to call common C APIs from Swift. This also works for array values. For example: var hostName = [CChar](repeating: 0, count: 256) gethostname(&hostName, hostName.count) print(String(cString: hostName)) // printed: slimey.local. In this code the ampersand denotes a conversion from [CChar] to an UnsafeMutablePointer<CChar> that points to the base of the array. While this is convenient, it’s potentially misleading, especially if you come from a C background. In C-based languages, using ampersand in this way yields a pointer to the value that’s valid until the value gets deallocated. That’s not the case in Swift. Rather, the pointer generated by the ampersand syntax is only valid for the duration of that function call. To understand why that’s the case, consider this code: struct TimeInTwoParts { var sec: time_t = 0 var usec: Int32 = 0 var combined: timeval { get { timeval(tv_sec: sec, tv_usec: usec) } set { sec = newValue.tv_sec usec = newValue.tv_usec } } } var time = TimeInTwoParts() gettimeofday(&time.combined, nil) // line A print(time.combined) // printed: timeval(tv_sec: 1590743484, tv_usec: 89118) print(time.sec) // printed: 1590743484 print(time.usec) // printed: 89118 Here combined is a computed property that has no independent existence in memory. Thus, it simply makes no sense to take the address of it. So, how does ampersand deal with this? Under the covers the Swift compiler expands line A to something like this: var tmp = time.combined gettimeofday(&tmp, nil) time.combined = tmp Once you understand this it’s clear why the resulting pointer is only valid for the duration of the call: As soon as Swift cleans up tmp, the pointer becomes invalid. A Gotcha This automatic conversion can be a nasty gotcha. Consider this code: var tv = timeval() let tvPtr = UnsafeMutablePointer(&tv) // line A // ^~~~~~~~~~~~~~~~~~~~~~~~~ // Initialization of 'UnsafeMutablePointer<timeval>' results in a dangling pointer gettimeofday(tvPtr, nil) // line B This results in undefined behaviour because the pointer generated by the ampersand on line A is no longer valid when it’s used on line B. In some cases, like this one, the later Swift compiler is able to detect this problem and warn you about it. In other cases you’re not so lucky. Consider this code: guard let f = fopen("tmp.txt", "w") else { … } var buf = [CChar](repeating: 0, count: 1024) setvbuf(f, &buf, _IOFBF, buf.count) // line A let message = [UInt8]("Hello Crueld World!".utf8) fwrite(message, message.count, 1, f) // line B fclose(f) // line C This uses setvbuf to apply a custom buffer to the file handle. The file handle uses this buffer until after the close on line C. However, the pointer created by the ampersand on line A only exists for the duration of the setvbuf call. When the code calls fwrite on line B the buffer pointer is no longer valid and things end badly. Unfortunately the compiler isn’t able to detect this problem. Worse yet, the code might actually work initially, and then stop working as you change optimisation settings, update the compiler, change unrelated code, and so on. Another Gotcha There is another gotcha associated with the ampersand syntax. Consider this code: class AtomicCounter { var count: Int32 = 0 func increment() { OSAtomicAdd32(1, &count) } } This looks like it’ll implement an atomic counter but there’s no guarantee that the counter will be atomic. To understand why, apply the tmp transform from earlier: class AtomicCounter { var count: Int32 = 0 func increment() { var tmp = count OSAtomicAdd32(1, &tmp) count = tmp } } So each call to OSAtomicAdd32 could potentially be operating on a separate copy of the counter that’s then assigned back to count. This undermines the whole notion of atomicity. Again, this might work in some builds of your product and then fail in other builds. Note The above discussion is now theoretical because Swift 6 added a Synchronization module that includes comprehensive support for atomics. That module also has a Mutex type (if you need a mutex on older platforms, check out OSAllocatedUnfairLock). These constructs use various different mechanisms to ensure that the underlying value has a stable address. Summary So, to summarise: Swift’s ampersand syntax has very different semantics from the equivalent syntax in C. When you use an ampersand to convert from a value to a pointer as part of a function call, make sure that the called function doesn’t use the pointer after it’s returned. It is not safe to use the ampersand syntax for functions where the exact pointer matters. It’s Not Just Ampersands There’s one further gotcha related to arrays. The gethostname example above shows that you can use an ampersand to pass the base address of an array to a function that takes a mutable pointer. Swift supports two other implicit conversions like this: From String to UnsafePointer<CChar> — This allows you to pass a Swift string to an API that takes a C string. For example: let greeting = "Hello Cruel World!" let greetingLength = strlen(greeting) print(greetingLength) // printed: 18 From Array<Element> to UnsafePointer<Element> — This allows you to pass a Swift array to a C API that takes an array (in C, arrays are typically represented as a base pointer and a length). For example: let charsUTF16: [UniChar] = [72, 101, 108, 108, 111, 32, 67, 114, 117, 101, 108, 32, 87, 111, 114, 108, 100, 33] print(charsUTF16) let str = CFStringCreateWithCharacters(nil, charsUTF16, charsUTF16.count)! print(str) // prints: Hello Cruel World! Note that there’s no ampersand in either of these examples. This technique only works for UnsafePointer parameters (as opposed to UnsafeMutablePointer parameters), so the called function can’t modify its buffer. As the ampersand is there to indicate that the value might be modified, it’s not used in this immutable case. However, the same pointer lifetime restriction applies: The pointer passed to the function is only valid for the duration of that function call. If the function keeps a copy of that pointer and then uses it later on, Bad Things™ will happen. Consider this code: func printAfterDelay(_ str: UnsafePointer<CChar>) { print(strlen(str)) // printed: 18 DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { print(strlen(str)) // printed: 0 } } let greeting = ["Hello", "Cruel", "World!"].joined(separator: " ") printAfterDelay(greeting) dispatchMain() The second call to strlen yields undefined behaviour because the pointer passed to printAfterDelay(_:) becomes invalid once printAfterDelay(_:) returns. In this specific example the memory pointed to by str happened to contain a zero, and hence strlen returned 0 but that’s not guaranteed. The str pointer is dangling, so you might get any result from strlen, including a crash. Advice So, what can you do about this? There’s two basic strategies here: Extend the lifetime of the pointer Manual memory management Extending the Pointer’s Lifetime The first strategy makes sense when you have a limited number of pointers and their lifespan is limited. For example, you can fix the setvbuf code from above by changing it to: let message = [UInt8]("Hello Crueld World!".utf8) guard let f = fopen("tmp.txt", "w") else { … } var buf = [CChar](repeating: 0, count: 1024) buf.withUnsafeMutableBufferPointer { buf in setvbuf(f, buf.baseAddress!, _IOFBF, buf.count) fwrite(message, message.count, 1, f) fclose(f) } This version of the code uses withUnsafeMutableBufferPointer(_:). That calls the supplied closure and passes it a pointer (actually an UnsafeMutableBufferPointer) that’s valid for the duration of that closure. As long as you only use that pointer inside the closure, you’re safe! There are a variety of other routines like withUnsafeMutableBufferPointer(_:), including: The withUnsafeMutablePointer(to:_:) function The withUnsafeBufferPointer(_:), withUnsafeMutableBufferPointer(_:), withUnsafeBytes(_:), and withUnsafeMutableBytes(_:) methods on Array The withUnsafeBytes(_:) and withUnsafeMutableBytes(_:) methods on Data The withCString(_:) and withUTF8(_:) methods on String. Manual Memory Management If you have to wrangle an unbounded number of pointers — or the lifetime of your pointer isn’t simple, for example when calling an asynchronous call — you must revert to manual memory management. Consider the following code, which is a Swift-friendly wrapper around posix_spawn: func spawn(arguments: [String]) throws -> pid_t { var argv = arguments.map { arg -> UnsafeMutablePointer<CChar>? in strdup(arg) } argv.append(nil) defer { argv.forEach { free($0) } } var pid: pid_t = 0 let success = posix_spawn(&pid, argv[0], nil, nil, argv, environ) == 0 guard success else { throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno), userInfo: nil) } return pid } This code can’t use the withCString(_:) method on String because it has to deal with an arbitrary number of strings. Instead, it uses strdup to copy each string to its own manually managed buffer. And, as these buffers are manually managed, is has to remember to free them. Change History 2024-12-11 Added a note about the Synchronization module. Made various editorial changes. 2021-02-24 Fixed the formatting. Added links to the WWDC 2021 sessions. Fixed the feedback advice. Minor editorial changes. 2020-06-01 Initial version.
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9.8k
Dec ’24
Passkey Creation SDK does not return Timeout Error on FaceID authentication times out.
We would like to show a user-friendly message but can not. Description: When attempting to create a duplicate passkey using the ASAuthrorizationController in iOS, the Face ID authentication times out SDK does not return a timeout specific error. Instead, it directly returns an error stating that duplicate passkey cannot be created. SDK to first handle the FaceID timeout case and provide a distinct timeout error so we can gracefully manage this scenario before the duplicate passkey validation occurs. Steps to Reproduce: Implement passkey creation flow using ASAuthorizationController. Attempt to register a duplicate passkey (e.g., using the same user ID and challenge). Let FaceID prompt timeout (do not interact with the authentication prompt).
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244
Dec ’24
Swift Package Manager – Support for Multiple Targets with Distinct Localization Files
I am an SDK provider working with Swift Package Manager (SPM) to deliver libraries for iOS developers. My SDK currently uses SPM targets to modularize functionality. However, SPM enforces strict resource bundling, which prevents me from efficiently offering multiple targets—each with a different set of localization files—in a single package. Current Limitation: When multiple SPM targets share the same source and resource directory but require distinct sets of .lproj localization folders (for app size or client requirements), SPM raises “overlapping sources” errors. The only workaround is to manually split resource directories or have clients prune localizations post-build, which is inefficient and error-prone. Feature Request: Please consider adding native support in Swift Package Manager for: Defining multiple targets within a single package that can process overlapping source/resource directories, Each target specifying a distinct subset of localization resource files via the exclude or a new designated parameter, Enabling efficient modular delivery of SDKs to clients needing different localization payloads, without redundant resource duplication or error-prone manual pruning. Support for this feature would greatly ease SDK distribution, lower app sizes, and improve package maintainability for iOS and all Swift platforms.
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Swift Concurrency Proposal Index
https://developer.apple.com/forums/thread/768776 Swift concurrency is an important part of my day-to-day job. I created the following document for an internal presentation, and I figured that it might be helpful for others. If you have questions or comments, put them in a new thread here on DevForums. Use the App & System Services > Processes & Concurrency topic area and tag it with both Swift and Concurrency. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Swift Concurrency Proposal Index This post summarises the Swift Evolution proposals that went into the Swift concurrency design. It covers the proposal that are implemented in Swift 6.2, plus a few additional ones that aren’t currently available. The focus is here is the Swift Evolution proposals. For general information about Swift concurrency, see the documentation referenced by Concurrency Resources. Swift 6.0 The following Swift Evolution proposals form the basis of the Swift 6.0 concurrency design. SE-0176 Enforce Exclusive Access to Memory link: SE-0176 notes: This defines the “Law of Exclusivity”, a critical foundation for both serial and concurrent code. SE-0282 Clarify the Swift memory consistency model ⚛︎ link: SE-0282 notes: This defines Swift’s memory model, that is, the rules about what is and isn’t allowed when it comes to concurrent memory access. SE-0296 Async/await link: SE-0296 introduces: async functions, async, await SE-0297 Concurrency Interoperability with Objective-C link: SE-0297 notes: Specifies how Swift imports an Objective-C method with a completion handler as an async method. Explicitly allows @objc actors. SE-0298 Async/Await: Sequences link: SE-0298 introduces: AsyncSequence, for await syntax notes: This just defines the AsyncSequence protocol. For one concrete implementation of that protocol, see SE-0314. SE-0300 Continuations for interfacing async tasks with synchronous code link: SE-0300 introduces: CheckedContinuation, UnsafeContinuation notes: Use these to create an async function that wraps a legacy request-reply concurrency construct. SE-0302 Sendable and @Sendable closures link: SE-0302 introduces: Sendable, @Sendable closures, marker protocols SE-0304 Structured concurrency link: SE-0304 introduces: unstructured and structured concurrency, Task, cancellation, CancellationError, withTaskCancellationHandler(…), sleep(…), withTaskGroup(…), withThrowingTaskGroup(…) notes: For the async let syntax, see SE-0317. For more ways to sleep, see SE-0329 and SE-0374. For discarding task groups, see SE-0381. SE-0306 Actors link: SE-0306 introduces: actor syntax notes: For actor-isolated parameters and the nonisolated keyword, see SE-0313. For global actors, see SE-0316. For custom executors and the Actor protocol, see SE-0392. SE-0311 Task Local Values link: SE-0311 introduces: TaskLocal SE-0313 Improved control over actor isolation link: SE-0313 introduces: isolated parameters, nonisolated SE-0314 AsyncStream and AsyncThrowingStream link: SE-0314 introduces: AsyncStream, AsyncThrowingStream, onTermination notes: These are super helpful when you need to publish a legacy notification construct as an async stream. For a simpler API to create a stream, see SE-0388. SE-0316 Global actors link: SE-0316 introduces: GlobalActor, MainActor notes: This includes the @MainActor syntax for closures. SE-0317 async let bindings link: SE-0317 introduces: async let syntax SE-0323 Asynchronous Main Semantics link: SE-0323 SE-0327 On Actors and Initialization link: SE-0327 notes: For a proposal to allow access to non-sendable isolated state in a deinitialiser, see SE-0371. SE-0329 Clock, Instant, and Duration link: SE-0329 introduces: Clock, InstantProtocol, DurationProtocol, Duration, ContinuousClock, SuspendingClock notes: For another way to sleep, see SE-0374. SE-0331 Remove Sendable conformance from unsafe pointer types link: SE-0331 SE-0337 Incremental migration to concurrency checking link: SE-0337 introduces: @preconcurrency, explicit unavailability of Sendable notes: This introduces @preconcurrency on declarations, on imports, and on Sendable protocols. For @preconcurrency conformances, see SE-0423. SE-0338 Clarify the Execution of Non-Actor-Isolated Async Functions link: SE-0338 note: This change has caught a bunch of folks by surprise and there’s a discussion underway as to whether to adjust it. SE-0340 Unavailable From Async Attribute link: SE-0340 introduces: noasync availability kind SE-0343 Concurrency in Top-level Code link: SE-0343 notes: For how strict concurrency applies to global variables, see SE-0412. SE-0374 Add sleep(for:) to Clock link: SE-0374 notes: This builds on SE-0329. SE-0381 DiscardingTaskGroups link: SE-0381 introduces: DiscardingTaskGroup, ThrowingDiscardingTaskGroup notes: Use this for task groups that can run indefinitely, for example, a network server. SE-0388 Convenience Async[Throwing]Stream.makeStream methods link: SE-0388 notes: This builds on SE-0314. SE-0392 Custom Actor Executors link: SE-0392 introduces: Actor protocol, Executor, SerialExecutor, ExecutorJob, assumeIsolated(…) notes: For task executors, a closely related concept, see SE-0417. For custom isolation checking, see SE-0424. SE-0395 Observation link: SE-0395 introduces: Observation module, Observable notes: While this isn’t directly related to concurrency, it’s relationship to Combine, which is an important exising concurrency construct, means I’ve included it in this list. SE-0401 Remove Actor Isolation Inference caused by Property Wrappers link: SE-0401, commentary availability: upcoming feature flag: DisableOutwardActorInference SE-0410 Low-Level Atomic Operations ⚛︎ link: SE-0410 introduces: Synchronization module, Atomic, AtomicLazyReference, WordPair SE-0411 Isolated default value expressions link: SE-0411, commentary SE-0412 Strict concurrency for global variables link: SE-0412 introduces: nonisolated(unsafe) notes: While this is a proposal about globals, the introduction of nonisolated(unsafe) applies to “any form of storage”. SE-0414 Region based Isolation link: SE-0414, commentary notes: To send parameters and results across isolation regions, see SE-0430. SE-0417 Task Executor Preference link: SE-0417, commentary introduces: withTaskExecutorPreference(…), TaskExecutor, globalConcurrentExecutor notes: This is closely related to the custom actor executors defined in SE-0392. SE-0418 Inferring Sendable for methods and key path literals link: SE-0418, commentary availability: upcoming feature flag: InferSendableFromCaptures notes: The methods part of this is for “partial and unapplied methods”. SE-0420 Inheritance of actor isolation link: SE-0420, commentary introduces: #isolation, optional isolated parameters notes: This is what makes it possible to iterate over an async stream in an isolated async function. SE-0421 Generalize effect polymorphism for AsyncSequence and AsyncIteratorProtocol link: SE-0421, commentary notes: Previously AsyncSequence used an experimental mechanism to support throwing and non-throwing sequences. This moves it off that. Instead, it uses an extra Failure generic parameter and typed throws to achieve the same result. This allows it to finally support a primary associated type. Yay! SE-0423 Dynamic actor isolation enforcement from non-strict-concurrency contexts link: SE-0423, commentary introduces: @preconcurrency conformance notes: This adds a number of dynamic actor isolation checks (think assumeIsolated(…)) to close strict concurrency holes that arise when you interact with legacy code. SE-0424 Custom isolation checking for SerialExecutor link: SE-0424, commentary introduces: checkIsolation() notes: This extends the custom actor executors introduced in SE-0392 to support isolation checking. SE-0430 sending parameter and result values link: SE-0430, commentary introduces: sending notes: Adds the ability to send parameters and results between the isolation regions introduced by SE-0414. SE-0431 @isolated(any) Function Types link: SE-0431, commentary, commentary introduces: @isolated(any) attribute on function types, isolation property of functions values notes: This is laying the groundwork for SE-NNNN Closure isolation control. That, in turn, aims to bring the currently experimental @_inheritActorContext attribute into the language officially. SE-0433 Synchronous Mutual Exclusion Lock 🔒 link: SE-0433 introduces: Mutex SE-0434 Usability of global-actor-isolated types link: SE-0434, commentary availability: upcoming feature flag: GlobalActorIsolatedTypesUsability notes: This loosen strict concurrency checking in a number of subtle ways. Swift 6.1 Swift 6.1 has the following additions. Vision: Improving the approachability of data-race safety link: vision SE-0442 Allow TaskGroup’s ChildTaskResult Type To Be Inferred link: SE-0442, commentary notes: This represents a small quality of life improvement for withTaskGroup(…) and withThrowingTaskGroup(…). SE-0449 Allow nonisolated to prevent global actor inference link: SE-0449, commentary notes: This is a straightforward extension to the number of places you can apply nonisolated. Swift 6.2 Xcode 26 beta has two new build settings: Approachable Concurrency enables the following feature flags: DisableOutwardActorInference, GlobalActorIsolatedTypesUsability, InferIsolatedConformances, InferSendableFromCaptures, and NonisolatedNonsendingByDefault. Default Actor Isolation controls SE-0466 Swift 6.2, still in beta, has the following additions. SE-0371 Isolated synchronous deinit link: SE-0371, commentary introduces: isolated deinit notes: Allows a deinitialiser to access non-sendable isolated state, lifting a restriction imposed by SE-0327. SE-0457 Expose attosecond representation of Duration link: SE-0457 introduces: attoseconds, init(attoseconds:) SE-0461 Run nonisolated async functions on the caller’s actor by default link: SE-0461 availability: upcoming feature flag: NonisolatedNonsendingByDefault introduces: nonisolated(nonsending), @concurrent notes: This represents a significant change to how Swift handles actor isolation by default, and introduces syntax to override that default. SE-0462 Task Priority Escalation APIs link: SE-0462 introduces: withTaskPriorityEscalationHandler(…) notes: Code that uses structured concurrency benefits from priority boosts automatically. This proposal exposes APIs so that code using unstructured concurrency can do the same. SE-0463 Import Objective-C completion handler parameters as @Sendable link: SE-0463 notes: This is a welcome resolution to a source of much confusion. SE-0466 Control default actor isolation inference link: SE-0466, commentary availability: not officially approved, but a de facto part of Swift 6.2 introduces: -default-isolation compiler flag notes: This is a major component of the above-mentioned vision document. SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation link: SE-0468 notes: This is an obvious benefit when you’re juggling a bunch of different async streams. SE-0469 Task Naming link: SE-0469 introduces: name, init(name:…) SE-0470 Global-actor isolated conformances link: SE-0470 availability: upcoming feature flag: InferIsolatedConformances introduces: @SomeActor protocol conformance notes: This is particularly useful when you want to conform an @MainActor type to Equatable, Hashable, and so on. SE-0471 Improved Custom SerialExecutor isolation checking for Concurrency Runtime link: SE-0471 notes: This is a welcome extension to SE-0424. SE-0472 Starting tasks synchronously from caller context link: SE-0472 introduces: immediate[Detached](…), addImmediateTask[UnlessCancelled](…), notes: This introduces the concept of an immediate task, one that initially uses the calling execution context. This is one of those things where, when you need it, you really need it. But it’s hard to summary when you might need it, so you’ll just have to read the proposal (-: In Progress The proposals in this section didn’t make Swift 6.2. SE-0406 Backpressure support for AsyncStream link: SE-0406 availability: returned for revision notes: Currently AsyncStream has very limited buffering options. This was a proposal to improve that. This feature is still very much needed, but the outlook for this proposal is hazy. My best guess is that something like this will land first in the Swift Async Algorithms package. See this thread. SE-NNNN Closure isolation control link: SE-NNNN introduces: @inheritsIsolation availability: not yet approved notes: This aims to bring the currently experimental @_inheritActorContext attribute into the language officially. It’s not clear how this will play out given the changes in SE-0461. Revision History 2025-09-02 Updated for the upcoming release Swift 6.2. 2025-04-07 Updated for the release of Swift 6.1, including a number of things that are still in progress. 2024-11-09 First post.
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Animatable AnyInsettableShape
System provides AnyShape type erasure that animates correctly. But system doesn't provide AnyInsettableShape. Here is my implementation of AnyInsettableShape (and AnyAnimatableData that is needed to support animation). Let me know if there is simpler solution. struct AnyInsettableShape: InsettableShape { private let _path: (CGRect) -> Path private let _inset: (CGFloat) -> AnyInsettableShape private let _getAnimatableData: () -> AnyAnimatableData private let _setAnimatableData: (_ data: AnyAnimatableData) -> AnyInsettableShape init<S>(_ shape: S) where S : InsettableShape { _path = { shape.path(in: $0) } _inset = { AnyInsettableShape(shape.inset(by: $0)) } _getAnimatableData = { AnyAnimatableData(shape.animatableData) } _setAnimatableData = { data in guard let otherData = data.rawValue as? S.AnimatableData else { assertionFailure(); return AnyInsettableShape(shape) } var shape = shape shape.animatableData = otherData return AnyInsettableShape(shape) } } var animatableData: AnyAnimatableData { get { _getAnimatableData() } set { self = _setAnimatableData(newValue) } } func path(in rect: CGRect) -> Path { _path(rect) } func inset(by amount: CGFloat) -> some InsettableShape { _inset(amount) } } struct AnyAnimatableData : VectorArithmetic { init<T : VectorArithmetic>(_ value: T) { self.init(optional: value) } private init<T : VectorArithmetic>(optional value: T?) { rawValue = value _scaleBy = { factor in (value != nil) ? AnyAnimatableData(value!.scaled(by: factor)) : .zero } _add = { other in AnyAnimatableData(value! + (other.rawValue as! T)) } _subtract = { other in AnyAnimatableData(value! - (other.rawValue as! T)) } _equal = { other in value! == (other.rawValue as! T) } _magnitudeSquared = { (value != nil) ? value!.magnitudeSquared : .zero } _zero = { AnyAnimatableData(T.zero) } } fileprivate let rawValue: (any VectorArithmetic)? private let _scaleBy: (_: Double) -> AnyAnimatableData private let _add: (_ other: AnyAnimatableData) -> AnyAnimatableData private let _subtract: (_ other: AnyAnimatableData) -> AnyAnimatableData private let _equal: (_ other: AnyAnimatableData) -> Bool private let _magnitudeSquared: () -> Double private let _zero: () -> AnyAnimatableData mutating func scale(by rhs: Double) { self = _scaleBy(rhs) } var magnitudeSquared: Double { _magnitudeSquared() } static let zero = AnyAnimatableData(optional: nil as Double?) @inline(__always) private var isZero: Bool { rawValue == nil } static func + (lhs: AnyAnimatableData, rhs: AnyAnimatableData) -> AnyAnimatableData { guard let (lhs, rhs) = fillZeroTypes(lhs, rhs) else { return .zero } return lhs._add(rhs) } static func - (lhs: AnyAnimatableData, rhs: AnyAnimatableData) -> AnyAnimatableData { guard let (lhs, rhs) = fillZeroTypes(lhs, rhs) else { return .zero } return lhs._subtract(rhs) } static func == (lhs: AnyAnimatableData, rhs: AnyAnimatableData) -> Bool { guard let (lhs, rhs) = fillZeroTypes(lhs, rhs) else { return true } return lhs._equal(rhs) } @inline(__always) private static func fillZeroTypes(_ lhs: AnyAnimatableData, _ rhs: AnyAnimatableData) -> (AnyAnimatableData, AnyAnimatableData)? { switch (!lhs.isZero, !rhs.isZero) { case (true, true): (lhs, rhs) case (true, false): (lhs, lhs._zero()) case (false, true): (rhs._zero(), rhs) case (false, false): nil } } }
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422
Dec ’24
The compiler is unable to type-check this expression in reasonable time
This is one of the worst errors you can encounter while developing with Xcode. It looks like it's related to a problem inside the compiler itself: when there are lot of lines of code, it becomes unable to identify them all and start asking you to break down the code in smaller pieces. Sometimes you can, sometimes not. First of all, in your code there is FOR SURE an error, so in case of the second option, begin commenting entires sections of your code: this can lead to two options: You commented a section that contains the error: Xcode give you the preview and you check the commented section to find the error You commented enough code to let the compiler do its job, and you'll have the normal error reported in your code: again, fix it! Once errors have been fixed, normally you can uncomment what you excluded and all will go up and ok again. The most common errors that can lead to this behavior (but it's just a hint) are those involving parameters got or passed to other SwiftUI objects: parameters label (mistyped, missing, exceeding) parameters values (not $/& present, $/& present but not required) parameters types (you passed a wrong type) Well, I hope that this post could be useful to others that, like I did, are struggling a lot to understand the exact nature of this peculiar error. Code well and Prosper!
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1
592
Oct ’24
Decryption failure - Migrated from Objective-C to Swift (AES256 Decryption failure in swift language)
Decrypting Data to String Conversion failure Development environment: Xcode 15.4, macOS 14.7 Run-time configuration: iOS 15.8.1 & 16.0.1 DESCRIPTION OF PROBLEM We were using objective C implementation of CCCrypt(see below) in our app earlier which we migrated to swift implementation recently. We convert the byte array that CCCrypt returns into Data, and data to string to read the decrypted value. It works perfectly fine in Objective C, whereas with new swift implementation this conversion is failing, it looks like CCCrypt is returning byte array with few non UTF8 characters and that conversion is failing in swift since Objective C is more tolerant with this conversion and converts the byte array to Data and then to string even though there are few imperfect UTF characters in the array. Objective C CCCryptorStatus CCCrypt( CCOperation op, /* kCCEncrypt, etc. / CCAlgorithm alg, / kCCAlgorithmAES128, etc. / CCOptions options, / kCCOptionPKCS7Padding, etc. */ const void *key, size_t keyLength, const void iv, / optional initialization vector */ const void dataIn, / optional per op and alg */ size_t dataInLength, void dataOut, / data RETURNED here */ size_t dataOutAvailable, size_t *dataOutMoved) API_AVAILABLE(macos(10.4), ios(2.0)); Swift Code CCCrypt(_ op: CCOperation, _ alg: CCAlgorithm, _ options: CCOptions, _ key: UnsafeRawPointer!, _ keyLength: Int, _ iv: UnsafeRawPointer!, _ dataIn: UnsafeRawPointer!, _ dataInLength: Int, _ dataOut: UnsafeMutableRawPointer!, _ dataOutAvailable: Int, _ dataOutMoved: UnsafeMutablePointer!) -> CCCryptorStatus Data to String Conversion String(data: decryptedData, encoding: .utf8) STEPS TO REPRODUCE Able to reproduce on below devices iPhone - 7 OS Version 15.8.1 iPhone 14- Pro OS Version 16.0.2 iPhone 15 iOS 18.0.1 **Decryption method return "Data" and converting into string using ".utf8" but String conversion is failing on above devices and some other devices as well. Decryption failure not occurring always. ** Below code used for String conversion String(data: decryptedData, encoding: .utf8)
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243
Dec ’24
AppleScriptLauncher Menu App
I'm primarily an AppleScript writer and only a novice programmer, using ChatGPT to help me with the legwork. It has helped me to write a functioning app that builds a menu structure based on the scripts I have in the Scripts directory used in the script menu and then runs the applescripts. When I distribute the app to my desktop and run it, the scripts that access other apps, like InDesign will cause it to launch, but not actually do anything. I included the ids for each app in the entitlements dictionary and have given the app full disk access in system settings, but it's not functioning as I'd expect. I know there are apps like Alfred that allow you to run scripts from a keystroke, but I'm building this for others I work with so they can also access info about each script, what it does, and how to use it from the menu, as well as key commands to run them. Not sure what else to say, but if this sounds like a simple fix to anyone, please let me know.
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0
433
Dec ’24
Getting error on xcode 15.3 underlying Objective-C module 'FirebaseSharedSwift' not found
underlying Objective-C module 'FirebaseSharedSwift' not found aymodazhnyneylcscdggrsgjocui/Build/Intermediates.noindex/Pods.build/Debug-iphonesimulator/FirebaseSharedSwift.build/Objects-normal/x86_64/FirebaseSharedSwift.private.swiftinterface:5:19: underlying Objective-C module 'FirebaseSharedSwift' not found Command SwiftCompile failed with a nonzero exit code
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0
492
Oct ’24
orientation transaction token
Hello Im having an error in swiftUI project of mine. I use fullscreencover to navigate through views. Normally it s been working but one point it doesn't. I go through MainMenu -> SomeOtherView -> GameView -> AfterGameView -> SomeOtherView -> MainMenu. When it comes to mainmenu at last, it s showing main menu for a glimpse of a look and then goes back to GameView. In console an error took my notice. > A new orientation transaction token is being requested while a valid one already exists. reason=Fullscreen transition (dismissing): fromVC=<_TtGC7SwiftUI29PresentationHostingControllerVS_7AnyView_: 0x10795ca00>; toVC=<_TtGC7SwiftUI29PresentationHostingControllerVS_7AnyView_: 0x1071c3400>;; windowOrientation=portrait; sceneOrientation=portrait; existingTransaction=<_UIForcedOrientationTransactionToken: 0x600001804a40; state: active; originalOrientation: portrait (1)> Cant really finding the solution. Need help asap I will release a bug update to Appstore.
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447
Jan ’25
SwifUI. Short way for using modifier methods
These helper methods allow to use modifier methods in standard for SwiftUI short way. extension View { @inline(__always) func modify(_ block: (_ view: Self) -> some View) -> some View { block(self) } @inline(__always) func modify<V : View, T>(_ block: (_ view: Self, _ data: T) -> V, with data: T) -> V { block(self, data) } } _ DISCUSSION Suppose you have modifier methods: func addBorder(view: some View) -> some View { view.padding().border(Color.red, width: borderWidth) } func highlight(view: some View, color: Color) -> some View { view.border(Color.red, width: borderWidth).overlay { color.opacity(0.3) } } _ Ordinar Decision Your code may be like this: var body: some View { let image = Image(systemName: "globe") let borderedImage = addBorder(view: image) let highlightedImage = highlight(view: borderedImage, color: .red) let text = Text("Some Text") let borderedText = addBorder(view: text) let highlightedText = highlight(view: borderedText, color: .yellow) VStack { highlightedImage highlightedText } } This code doesn't look like standard SwiftUI code. _ Better Decision Described above helper methods modify(:) and modify(:,with:) allow to write code in typical for SwiftUI short way: var body: some View { VStack { Image(systemName: "globe") .modify(addBorder) .modify(highlight, with: .red) Text("Some Text") .modify(addBorder) .modify(highlight, with: .yellow) } }
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405
Dec ’24
AVExportSession in Xcode16 - "exportAsynchronouslyWithCompletionHandler: more than once."
I’m experiencing a crash at runtime when trying to extract audio from a video. This issue occurs on both iOS 18 and earlier versions. The crash is caused by the following error: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '*** -[AVAssetExportSession exportAsynchronouslyWithCompletionHandler:] Cannot call exportAsynchronouslyWithCompletionHandler: more than once. (0x1851435ec 0x1826dd244 0x1970c09c0 0x214d8f358 0x214d95899 0x190a1c8b9 0x214d8efd9 0x30204cef5 0x302053ab9 0x190a5ae39) libc++abi: terminating due to uncaught exception of type NSException My previous code worked fine, but it's crashing with Swift 6. Does anyone know a solution for this? Previous code: func extractAudioFromVideo(from videoURL: URL, exportHandler: ((AVAssetExportSession, CurrentValueSubject<Float, Never>?) -> Void)? = nil, completion: @escaping (Swift.Result<URL, Error>) -> Void) { let asset = AVAsset(url: videoURL) // Create an AVAssetExportSession to export the audio track guard let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else { completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"]))) return } // Set the output file type and path guard let filename = videoURL.lastPathComponent.components(separatedBy: ["."]).first else { return } let outputURL = VideoUtils.getTempAudioExportUrl(filename) VideoUtils.deleteFileIfExists(outputURL.path) exportSession.outputFileType = .m4a exportSession.outputURL = outputURL let audioExportProgressPublisher = CurrentValueSubject<Float, Never>(0.0) if let exportHandler = exportHandler { exportHandler(exportSession, audioExportProgressPublisher) } // Periodically check the progress of the export session let timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { _ in audioExportProgressPublisher.send(exportSession.progress) } // Export the audio track asynchronously exportSession.exportAsynchronously { switch exportSession.status { case .completed: completion(.success(outputURL)) case .failed: completion(.failure(exportSession.error ?? NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown error occurred while exporting audio"]))) case .cancelled: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"]))) default: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown export session status"]))) } // Invalidate the timer when the export session completes or is cancelled timer.invalidate() } } ## New Code: func extractAudioFromVideo(from videoURL: URL, exportHandler: ((AVAssetExportSession, CurrentValueSubject<Float, Never>?) -> Void)? = nil, completion: @escaping (Swift.Result<URL, Error>) -> Void) { let asset = AVAsset(url: videoURL) // Create an AVAssetExportSession to export the audio track guard let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else { completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"]))) return } // Set the output file type and path guard let filename = videoURL.lastPathComponent.components(separatedBy: ["."]).first else { return } let outputURL = VideoUtils.getTempAudioExportUrl(filename) VideoUtils.deleteFileIfExists(outputURL.path) exportSession.outputFileType = .m4a exportSession.outputURL = outputURL let audioExportProgressPublisher = CurrentValueSubject<Float, Never>(0.0) if let exportHandler { exportHandler(exportSession, audioExportProgressPublisher) } let task = Task { if #available(iOS 18.0, *) { // Handle export for iOS 18 and later let states = exportSession.states(updateInterval: 0.1) for await state in states { switch state { case .pending, .waiting: break case .exporting(progress: let progress): print("Exporting: \(progress.fractionCompleted)") if progress.isFinished { completion(.success(outputURL)) } else if progress.isCancelled { completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"]))) } else { audioExportProgressPublisher.send(Float(progress.fractionCompleted)) } } } try await exportSession.export(to: outputURL, as: .m4a) // Only call export once } else { // Handle export for iOS versions below 18 let publishTimer = Timer.publish(every: 0.1, on: .main, in: .common) .autoconnect() .sink { [weak exportSession] _ in guard let exportSession = exportSession else { return } audioExportProgressPublisher.send(exportSession.progress) } // Only call export once await exportSession.export() // Handle the export session's status switch exportSession.status { case .completed: completion(.success(outputURL)) case .failed: completion(.failure(exportSession.error ?? NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown error occurred while exporting audio"]))) case .cancelled: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"]))) default: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown export session status"]))) } // Invalidate the timer when the export session completes or is cancelled publishTimer.cancel() } } task.cancel() }
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440
Dec ’24
traitCollectionDidChange iOS18
iOS18.2 / iPhone 16pro / Xcode 16.2 'traitCollectionDidChange' This function has been deprecated since ios17. However, in ios18, when I changed the app to the background state or changed it to the foreground state again, it was confirmed that the function worked. It hasn't been confirmed in ios17, but why is it only confirmed in ios18?
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610
Dec ’24
WKWebView missing page parts
Hi guys, I've been struggling for a few days with this really weird behaviour. We made an app for our e-commerce website and found out that a part of the product page is missing. For any reason, the header and first blocks of the page and footer are displayed, but then a massive part of the content is missing. This content is not loaded through ajax; that's why I don't understand why it's not displayed. You can see here 2 screenshots of what the page should look like and what the page looks like with WKWebView. I've been inspecting this with Safari; there isn't any blocking error in the console, and html elements are just empty. There is the div with class row and nothing in it. The same website is working perfectly with native Android Webview. If anyone has any clue to find out what's going wrong
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277
Jan ’25
Exposing Objective-C API to Swift inside a Framework (Private Framework API)
My framework has private Objective-C API that is only used within the framework. It should not be exposed in the public interface (so it shouldn't be imported in the umbrella header). To expose this API to Swift that's within the framework only the documentation seems to indicate that this needs to be imported in the umbrella header? Import Code Within a Framework Target To use the Objective-C declarations in files in the same framework target as your Swift code, configure an umbrella header as follows: 1.Under Build Settings, in Packaging, make sure the Defines Module setting for the framework target is set to Yes. 2.In the umbrella header, import every Objective-C header you want to expose to Swift. Swift sees every header you expose publicly in your umbrella header. The contents of the Objective-C files in that framework are automatically available from any Swift file within that framework target, with no import statements. Use classes and other declarations from your Objective-C code with the same Swift syntax you use for system classes. I would imagine that there must be a way to do this?
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265
Jul ’25
App Settings Not Appearing with Xcode 16.2
I recently encountered an issue with Xcode 16.2 while attempting to integrate Settings.bundle into a new app. I added Settings.bundle as a new file (using the provided template), but when I ran the app (the standard simple "Hello World" project), the expected three default controls (Name, Enabled, Slider) did not appear in the app's settings. To troubleshoot, I downgraded my system to macOS Sonoma 14.7.2 and Xcode 15.4 (on a 2023 Mac Mini, M2). After this downgrade, everything worked as expected. With a new project, adding Settings.bundle, and running the app, the settings entry for the app appeared, including the three default fields. This behavior suggests a potential issue or incompatibility with Xcode 16.2.
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438
Dec ’24