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is this a bug that NSDateFormatter knows about leap days but not about leap seconds?
let f = DateFormatter()
f.timeZone = TimeZone(identifier: "UTC")
f.dateFormat = "yyyy/MM/dd HH:mm:ss"
// last leap year
let t1 = f.date(from: "2020/02/29 00:00:00") // 2020-02-29 00:00:00 UTC
// last leap second
let t2 = f.date(from: "2016/12/31 23:59:60") // nil
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Given an arbitrary memory address how do I find (in runtime) the nature of memory block it belongs to?
For stack addresses I guess there's some "stack start" and "stack end" of the current thread. For other threads' stacks - I guess I'd have to enumerate all threads to get those ranges. I also found that I can use malloc_size and sometimes it gives me correct result (the size if non zero at least), although it doesn't give me the beginning of the block memory address belongs to. For anything else I have no clue at the moment.
Ideal method I am looking for:
struct MemoryBlock {
let type: MemoryBlockType // stack, heap, unmapped, etc
let start: UnsafeRawPointer
let size: Int
let attributes // e.g. red / write
}
func findMemoryBlock(_ address: UnsafeRawPointer) -> MemoryBlock
PS. the language doesn't matter (e.g. can be C) so long as this method works in a swift/obj-c app.
Our app has "allow arbitrary loads" in the "App Transport Security Settings" and generally allows both "http" and "https" connections. I want to restrict basic authentication usage to secure connections only, what is the best way to do that?
I have URLSessionTaskDelegate's:
func urlSession(_ session: URLSession, task: URLSessionTask, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
where I can put the relevant logic, but how do I check if the connection attempt in question is happening over TLS or not? I can check task.currentRequest.url scheme being "http" vs "https", and port being nil vs 80 vs 443, but I hope there is a more robust check.
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https://developer.apple.com/documentation/foundation/urlcache
has this:
"Although URLCache instance methods can safely be called from multiple execution contexts at the same time, be aware that methods like cachedResponse(for:) and storeCachedResponse(_:for:) have an unavoidable race condition when attempting to read or write responses for the same request."
What does it mean "unavoidable"? If I put a lock (mutex / NSLock, or similar) in my wrappers on top of "cachedResponse" / "storeCachedResponse" would that avoid the mentioned race condition?
Also, what do they mean by "the same request"? A few examples below:
let url = URL(string: "https://www.apple.com")!
let req1 = URLRequest(url: url)
let req2 = req1 // perhaps "the same"
let req3 = URLRequest(url: url) // "the same"?
let req4 = URLRequest(url: req1.url!) // "the same"?
let req5 = URLRequest(url: url, cachePolicy: req1.cachePolicy, timeoutInterval: req1.timeoutInterval) // "the same"?
let req6 = URLRequest(url: url, cachePolicy: req1.cachePolicy, timeoutInterval: 1234) // "the same"?
let req7 = URLRequest(url: url, cachePolicy: .reloadIgnoringCacheData, timeoutInterval: req1.timeoutInterval) // "the same"?
assert(req1 == req2)
assert(req1 == req3)
assert(req1 == req4)
assert(req1 == req5)
assert(req1 == req6) // this is ok
assert(req1 == req7) // this fails
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Tried to ask as a comment in the other thread:
https://developer.apple.com/forums/thread/650386?answerId=628394022#reply-to-this-question
But can't leave a comment in there for some reason (the thread is locked?). Asking exactly the same question, now for iOS 15. Anything changed in this area?
When selecting a stroke path for object on PKCanvas, the option "Snap to Shape" appears.
I understand this function is still in beta and has not made available natively to other PencilKit app. Is there a way using Stroke API to call this function directly after the user hold pencil for half a second when stroke is done drawing, just like how it behaves in native apps?
Is it possible to use network from within iOS Thumbnail Extension?
I tried - it works fine under simulator, but I'm getting this error when running on real device:
networkd_settings_read_from_file Sandbox is preventing this process from reading networkd settings file at "/Library/Preferences/com.apple.networkd.plist", please add an exception.
Adding "App Transport Security Settings / Allow Arbitrary Loads" plist entry didn't help. As the error seems to be specific access to a particular file I tried adding "com.apple.security.temporary-exception.files.absolute-path.read-only" but it didn't help and looks like it couldn't help on iOS: "Note: This chapter describes property list keys specific to the macOS implementation of App Sandbox. They are not available in iOS."
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how do i make TextEditor autoscrolled? i want to implement a log view based on it - when the scroll position is at bottom, adding new lines shall autoscroll it upwards so the newly added lines are visible. and when the scroll position is not at bottom - adding new lines shall not autoscroll it.
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is JSONSerialization.jsonObject(with: inputStream) reliable? sometimes it works fine (e.g. with small objects) and sometimes it blocks forever (easier to get the block with big objects). yet sometimes it works ok even with big objects. tried to call it on a different queue - didn't help.
hello,
how do i create a virtual microphone on macOS that can be selected as a default input device in System Settings or in apps like FaceTime / QuickTime Player / Skype, etc?
is Audio HAL plugin the way to go?
i've seen this macOS 10.15 note: "Legacy Core Audio HAL audio hardware plug-ins are no longer supported. Use Audio Server plug-ins for audio drivers." though i am not sure if that's applicable, as i can think of these interpretations:
1 "Legacy Core Audio HAL audio hardware plug-ins are no longer supported (but you can still use non-legacy ones.)
2 "Legacy Core Audio HAL audio hardware plug-ins are no longer supported." (but you can still use non-hardware ones".)
3 "Legacy Core Audio HAL audio hardware plug-ins are no longer supported". (if you used that functionality to implement audio hardware drivers then your you can use Audio Server plug-ins instead, otherwise you are screwed.)
The "Audio Server plugin" documentation is minimalistic:
https://developer.apple.com/library/archive/qa/qa1811/_index.html
which leads to a 2013 sample code:
https://developer.apple.com/library/archive/samplecode/AudioDriverExamples/Introduction/Intro.html
and contains a "nullAudio" plugin and a kernel extension backed plugin - neither of those i wasn't able to resurrect (i'm on macOS Catalina now).
any hints?
hello,
i know i could be overly paranoid at times.. but
is this the case that i need to protect my global memory location (that i read from / write to) with read/write memory barriers even if i'm only accessing that location from a single serial DispatchQueue? considering the fact that GCD can pick a different thread to run operations on that queue, and a further fact that different threads can run on different cores and thus have different L1/L2 caches, so that the barrier unprotected write to a location in one code invocation (that runs on my serial queue, that happens to be bound to thread1/core1 at the time) might not yet be visible to a different invocation of my code that runs a bit later on the same serial GCD queue but it so happens that now it runs on thread2/core2, so that the barrier unprotected read from that global memory location returns some stale data?
is the answer any different if we consider a serial (maxConcurrentCount=1) OperationQueue instead of a serial dispatch queue?
finally, is the answer any different if we consider a single NSThread / pthread instead of a serial dispatch queue? can a single thread be bound to different cores during its lifetime? (e.g. work on one core, then sleep, then awake on a different core).
thank you.
hello,
i don't think it is provided by the system already so i'd like to implement a smart version of DispatchQueue.async function - the one that will not reschedule the block if i am already on the queue in question and call the block directly instead in this case.
extension DispatchQueue {
func asyncSmart(execute: @escaping () -> Void) {
if DispatchQueue.current === self { // ?????
execute()
} else {
async(execute: execute)
}
}
}
the immediate problem is that there is no way to get the current queue (in order to compare it with the queue parameter and do the logic branch).
anyone've been through it and solved this puzzle?
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i have a list like this:
id: 1, image: image1, title: title1, badge: 0
id: 2, image: image2, title: title2, badge: 0
id: 3, image: image3, title: title3, badge: 0
...
is my understanding correct that in order to do a smooth "expected" animation when I want to change both the badge of the item and its order i have to manually split this "big" update into two smaller updates (first change then move, or vice versa)?
this is somewhat surprising, i would expect a diffable implementation to have a notion of "identity" (in the example above it's "id") and calculate the differences based on that identity plus ite equivalence check rather than just based on the hash/equality check for the whole item.
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https://developer.apple.com/library/archive/qa/qa1811/_index.html
this is old, i know. can those in the know shed some light on whether the bit about temp/cached location still correct:
An AudioServerPlugIn operates in a limited environment. ... Further, the host process is sandboxed. As such, an AudioServerPlugIn may only read files in its bundle in addition to the system libraries and frameworks. It may not access user documents or write to any filesystem locations other than the system's cache and temporary directories as derived through Apple API.
i tried to write to temporary folder (obtained with NSTemporaryDirectory and also tried /tmp and /private/tmp) and cached folder (obtained with NSSearchPathForDirectoriesInDomains + cachesDirectory) but everything i tried resulted in permission errors.
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what is the best way for a HAL plugin to launch a helper app? i tried the obvious NSWorkspace's launch/openApplication those don't work. HAL plugin works in the context of coreaudiod which makes that tricky.
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i thought it is impossible to have CallKit show system UI for outgoing calls. but then i saw this:
"For incoming and outgoing calls, CallKit displays the same interfaces as the Phone app..."
https://developer.apple.com/documentation/callkit
how do i present it though? or is this a documentation error?
yetanotherme.