My assumption has always been that [NSApp runModalForWindow:] runs a modal window in NSModalPanelRunLoopMode.
However, while -[NSApplication _doModalLoop:peek:] seems to use NSModalPanelRunLoopMode when pulling out the next event to process via nextEventMatchingMask:untilDate:inMode:dequeue:, the current runloop doesn't seem to be running in that mode, so during -[NSApplication(NSEventRouting) sendEvent:] of the modal-specific event, NSRunLoop.currentRunLoop.currentMode returns kCFRunLoopDefaultMode.
From what I can tell, this means that any event processing code that e.g. uses [NSTimer addTimer:forMode:] based on the current mode will register a timer that will not fire until the modal session ends.
Is this a bug? Or if not, is the correct way to run a modal session something like this?
[NSRunLoop.currentRunLoop performInModes:@[NSModalPanelRunLoopMode] block:^{
[NSApp runModalForWindow:window];
}];
[NSRunLoop.currentRunLoop limitDateForMode:NSModalPanelRunLoopMode];
Alternatively, if the mode of the runloop should stay the same, I've seen suggestions to run modal sessions like this:
NSModalSession session = [NSApp beginModalSessionForWindow:theWindow];
for (;;) {
if ([NSApp runModalSession:session] != NSModalResponseContinue)
break;
[NSRunLoop.currentRunLoop limitDateForMode:NSModalPanelRunLoopMode];
}
[NSApp endModalSession:session];
Which would work around the fact that the timer/callbacks were scheduled in the "wrong" mode. But running NSModalPanelRunLoopMode during a modal session seems a bit scary. Won't that potentially break the modality?
UIKit
RSS for tagConstruct and manage graphical, event-driven user interfaces for iOS or tvOS apps using UIKit.
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I have this drawing app that I have been working on for the past few years when I have free time. I recently rebuilt the app in Metal to build out other brushes and improve performance, need to render 10000s of lines in realtime.
I’m running into this issue trying to create a uniform opacity per path. I have a solution but do not love it - as this is a realtime app and the solution could have some bottlenecks. If I just generate a triangle strip from touch points and do my best to smooth, resample, and handle miters I will always get some overlaps. See:
To create a uniform opacity I render to an offscreen texture with blending disabled. I then pre-multiply the color and draw that texture to a composite texture with blending on (I do this per path). This works but gets tricky when you introduce a textured brush, the edges of the texture in the frag shader cut out the line.
Pasted Graphic 1.png
Solution: I discard below a threshold
fragment float4 fragment_line(VertexOut in [[stage_in]],
texture2d<float> texture [[ texture(0) ]]) {
constexpr sampler s(coord::normalized, address::mirrored_repeat, filter::linear);
float2 texCoord = in.texCoord;
float4 texColor = texture.sample(s, texCoord);
if (texColor.a < 0.01) discard_fragment(); // may be slow (from what I read)
return in.color * texColor;
}
Better but still not perfect.
Question: I'm looking for better ways to create a uniform opacity per path. I tried .max blending but that will cause no blending of other paths. Any tips, ideas, much appreciated. If this is too detailed of a question just achieve.
I have created a custom class:
class TarifsHeaderFooterView: UITableViewHeaderFooterView { …}
With its init:
override init(reuseIdentifier: String?) {
super.init(reuseIdentifier: reuseIdentifier)
configureContents()
}
I register the custom header view in viewDidLoad of the class using the tableView. Table delegate and data source are defined in storyboard.
tarifsTableView.register(TarifsHeaderFooterView.self, forHeaderFooterViewReuseIdentifier: headerTarifsIdentifier)
And call it:
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let view = tableView.dequeueReusableHeaderFooterView(withIdentifier: headerTarifsIdentifier) as! TarifsHeaderFooterView
That works on iPhone (simulators and devices).
But it crashes on any iPad simulator, as tableView.dequeueReusableHeaderFooterView(withIdentifier: headerTarifsIdentifier) is found nil.
What difference between iPhone and iPad do I miss that explains this crash ?
PS: sorry for the messy message. It looks like the new "feature" of the forum to put a Copy code button on the code parts, causes the code sections to be put at the very end of the post, not at the place they should be.
Case-ID: 12591306
Use Xcode 16.x to compile an iPhone demo app and run it on an iPad (iPadOS 18.x) device or simulator.
Launch the iPhone app and activate Picture-in-Picture mode.
Attempt to input text; the system keyboard does not appear.
Compare the output of [[UIScreen mainScreen] bounds] before and after enabling Picture-in-Picture mode, notice the values change unexpectedly after enabling PiP.
This issue can be consistently reproduced on iPadOS 18.x when running an app built with Xcode 16.0 to Xcode 16.3RC(16E137).
Beginning April 24, 2025, apps uploaded to App Store Connect must be built with Xcode 16 or later using an SDK for iOS 18, iPadOS 18, tvOS 18, visionOS 2, or watchOS 11.Therefore, I urgently hope to receive a solution provided by Apple.
UIKit and SwiftUI each have their own strengths and weaknesses:
UIKit: More performant (e.g., UICollectionView).
SwiftUI: Easier to create shiny UI and animations.
My usual approach is to base my project on UIKit and use UIHostingController whenever I need to showcase visually rich UI or animations (such as in an onboarding presentation).
So far, this approach has worked well for me—it keeps the project clean while solving performance concerns effectively.
However, I was wondering: Has anyone tried the opposite approach?
Creating a project primarily in SwiftUI, then embedding UIKit when performance is critical.
If so, what has your experience been like? Would you recommend this approach?
I'm considering this for my next project but am unsure how well it would work in practice.
Hi team,
We have implemented a writing tool inside a WebView that allows users to type content in a textarea. When the "Show Writing Tools" button is clicked, an AI-powered editor opens. After clicking the "Rewrite" button, the AI modifies the text. However, when clicking the "Replace" button, the rewritten text does not update the original textarea.
Kindly check and help me
showButton.addTarget(self, action: #selector(showWritingTools(_:)), for: .touchUpInside)
@available(iOS 18.2, *)
optional func showWritingTools(_ sender: Any)
Note:
same cases working in TextView
pfa
I have found a system bug with UINavigationController, UIGestureRecognizerDelegate mainly the swipe back control.
I have reproduced this in many apps, while some that use custom swipe back i can not reproduce, however any app using default uikit/swift transitions i can reproduce the flicker/previous screen flashing
The Bug: a slight tap or series of quick taps anywhere on the screen (with the slightest (1-2pt -x)confuse the system into thinking its a swipe back gesture, however instead of pushing back to previous screen the UI flickers and flashes the previous screen. for a split second, very easy to reproduce.
on screens with lots of options of boxes to tap it happens quite often.
I have removed all custom "swipe back from anywhere" logic, all custom gesture logic, and can still reproduce by tapping the edge of the screen
with only UINavigationController, UIGestureRecognizerDelegate in my navigation controller.
Please let me know the best way to get in contact with someone at apple to either build an extension to prevent this flicker or if a developer has a fix but this is rarely talked about. (velocity limits etc do not work, and just make the gesture feel awful)
all the developers i have reached out too have looked into this and have said "its an ios bug, only fix is build a custom swipe back from anywhere, or wait for apple to fix it).... as a small indie app, building my own seems daunting
Recap: quick or taps with small x movement flash previous screen instead of pushing back or simply recognizing it as a tap and not flashing previous screen. this happens with no custom code default uikit/swift. Link me your app i can probably reproduce it, I have reproduced it in X(was hard), Retro(easy), and many more.
The goal is to have a smooth native swipe/drag back from anywhere gesture while preventing flicking on fast taps or short taps with minor x movement. i have tried everything from setting limits to -x, velocity limits etc. nothing fixes this.
happy hacking!
PS i hope someone at apple calls me and i can explain this and we can fix it for every app in an update.
I'm having an issue specifically with SwiftUI previews in my iOS project. The project builds and runs fine on devices and simulators (in Rosetta mode), but SwiftUI previews fail to load in both Rosetta and native arm64 simulator environments. The main error in the preview is related to the Alamofire dependency in my SiriKit Intents extension:
Module map file '[DerivedData path]/Build/Products/Debug-iphonesimulator/Alamofire/Alamofire.modulemap' not found
This error repeats for multiple Swift files within my SiriKit Intents extension. Additionally, I'm seeing:
Cannot load underlying module for 'Alamofire
Environment
Xcode version: 16.2
macOS version: Sonoma 14.7
Swift version: 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
Dependency management: CocoaPods
Alamofire version: 5.8
My project is a large, older codebase that contains a mix of UIKit, Objective-C and Swift
Architecture Issue: The project only builds successfully in Rosetta mode for simulators. SwiftUI previews are failing in both Rosetta and native arm64 environments. This suggests there may be a fundamental issue with how the preview system interacts with the project's architecture configuration. What I've Tried I've attempted several solutions without success:
Cleaning the build folder (⇧⌘K and Option+⇧⌘K)
Deleting derived data
Reinstalling dependencies
Restarting Xcode
Removing and re-adding Alamofire
SwiftUI provides the accessibilityCustomContent(_:_:) modifier to add additional accessibility information for an element. However, I couldn’t find a similar approach in UIKit.
Is there a way to achieve this in UIKit?
Since beta 4, Using TipKit causes the app to crash.
This was not the case in Beta 3.
My app uses UIKit
In our application we are using a Search bar in a pop over view and we have enabled Accessibility full keyboard access and we are using external keyboard. Now if the focus is on Searcher that time by next Tab key press Search bar will dismiss and focus needs to shift to the next UIElement.
I’m having a weird UIKit problem. I have a bunch of views in a UIScrollView and I add a UIContextMenuInteraction to all of them when the view is first loaded. Because they're in a scroll view, only some of the views are initially visible.
The interaction works great for any of the views that are initially on-screen, but if I scroll to reveal new subviews, the context menu interaction has no effect for those.
I used Xcode's View Debugger to confirm that my interaction is still saved in the view's interactions property, even for views that were initially off-screen and were then scrolled in.
What could be happening here?
Hello team i notice that we have a problem in our app that every time the user opens a Textfield the app freezes when the keyboard appears, this behavior was tracked down and it's a UI breaking design on a UIView
[this view it's expandable and is original size is 80]
[when it gets expanded 206.33]
this is the view code I change the colors to easy check the other's views created inside
private lazy var sharedUIPlaybackView: UIView = {
let containerView = UIView().withAutoLayout()
let propertySearchCriteria = PropertySearchCriteriaBuilder(hotelSearchParameters: viewModel.hotelSearchParameters).criteria
var swiftUIView: SwiftUIView<LodgingPlaybackWrapper>! = nil
swiftUIView = SwiftUIView(
LodgingPlaybackWrapper(propertySearchCriteria: propertySearchCriteria,
playbackUpdateNotificationSender: playbackUpdateNotificationSender,
componentHandler: { [weak self] componentId in
self?.componentReady(componentId)
}),
viewDidLayoutSubviewsCallback: { [weak self] in
let extraPadding = self?.playbackViewExtraPadding ?? Spacing.spacing8x
let newHeight = swiftUIView.frame.size.height + extraPadding
// if newHeight != self?.sharedUIPlaybackViewHeightConstraint?.constant {
// self?.sharedUIPlaybackViewHeightConstraint?.constant = 206.33
// }else {
// self?.sharedUIPlaybackViewHeightConstraint?.constant = 80
// }
}
).withAutoLayout().withAccessibilityIdentifier("test")
// sharedUIPlaybackViewHeightConstraint = containerView.heightAnchor.constraint(equalToConstant: 0)
// sharedUIPlaybackViewHeightConstraint?.isActive = true
containerView.backgroundColor = .blue
swiftUIView.backgroundColor = .red
containerView.addSubview(swiftUIView)
containerView.addConstraints([
swiftUIView.topAnchor.constraint(equalTo: containerView.topAnchor, constant: playbackViewTopConstant),
swiftUIView.leadingAnchor.constraint(equalTo: containerView.leadingAnchor, constant: Spacing.spacing4x),
swiftUIView.trailingAnchor.constraint(equalTo: containerView.trailingAnchor, constant: -Spacing.spacing4x),
swiftUIView.bottomAnchor.constraint(equalTo: containerView.bottomAnchor, constant: -Spacing.spacing3x),
swiftUIView.heightAnchor.constraint(equalToConstant: 206.33)
])
return containerView
}()
old devs created this function viewDidLayoutSubviewsCallback to connect user interaction on the wrapper and used on UIKit.
this is the part where the math on the function gets weird and messed up the code by crashing the view
viewDidLayoutSubviewsCallback: { [weak self] in
let extraPadding = self?.playbackViewExtraPadding ?? Spacing.spacing8x
let newHeight = swiftUIView.frame.size.height + extraPadding
if newHeight != self?.sharedUIPlaybackViewHeightConstraint?.constant {
self?.sharedUIPlaybackViewHeightConstraint?.constant = newHeight
}
}
).withAutoLayout().withAccessibilityIdentifier("test")
sharedUIPlaybackViewHeightConstraint = containerView.heightAnchor.constraint(equalToConstant: 0)
sharedUIPlaybackViewHeightConstraint?.isActive = true
I commented this math because is crashing the app and instead of giving a dynamical height I placed as a constant constraint as default height this is how I solved the problem of the UI, but I still need to update the view each time the user clicks and gets call by the method viewDidLayoutSubviewsCallback
what can I do?
I tried to add like a conditional on the method
if newHeight == 80 {
containerView.addConstraints([
swiftUIView.heightAnchor.constraint(equalToConstant: 80.0)
])
containerView.layoutIfNeeded()
}
else {
containerView.addConstraints([
swiftUIView.heightAnchor.constraint(equalToConstant: 206.33)
])
containerView.layoutIfNeeded()
}
like this but it didn't work
[this is how it looks with the constant value of 206.33]
[when it gets open looks good]
Our Apple TV provides UIImages with renderingMode forced to .alwaysTemplate (the images are also configured with "Render As" to "Template image" in the Asset catalog) to UIActions as UIMenuElement when building a UICollectionView UIContextMenuConfiguration.
Problem: these images are not displayed with vibrancy effect by the system.
The issue does not occur with system images (SVG from SF Catalog).
Here is a screenshot showing the issue with custom images ("Trailer" and "Remove from favourites"):
I don't know the underlying implementation of the context menu items image but UIImageView already implements the tintColorDidChange() method and the vibrancy should work if the UIImage is rendered as template.
According to my tests, the vibrancy is correctly applied when using Symbols sets instead of Images sets but I understand that custom images rendered as template should support it as-well, shouldn't they?
I’m trying to add the .header accessibility trait to a UISegmentedControl so that VoiceOver recognizes it accordingly. However, setting the trait using the following code doesn’t seem to have any effect:
segmentControl.accessibilityTraits = segmentControl.accessibilityTraits.union(.header)
Even after applying this, VoiceOver doesn’t announce it as a header. Is there any workaround or recommended approach to achieve this?
I set UIToolbar and UIBarButtonItem to UITextField placed on Xib, but when I run it on iOS18 iPad, the following error is output to Xcode Console, and UIPickerView set to UITextField.inputView is not displayed.
Error: this application, or a library it uses, has passed an invalid numeric value (NaN, or not-a-number) to CoreGraphics API and this value is being ignored. Please fix this problem.
If you want to see the backtrace, please set CG_NUMERICS_SHOW_BACKTRACE environmental variable.
Backtrace:
<CGPathAddLineToPoint+71>
<+[UIBezierPath _continuousRoundedRectBezierPath:withRoundedCorners:cornerRadii:segments:smoothPillShapes:clampCornerRadii:]
<+[UIBezierPath _continuousRoundedRectBezierPath:withRoundedCorners:cornerRadius:segments:]+175>
<+[UIBezierPath _roundedRectBezierPath:withRoundedCorners:cornerRadius:segments:legacyCorners:]+338>
<-[_UITextMagnifiedLoupeView layoutSubviews]+2233>
<__56-[_UITextMagnifiedLoupeView _updateCloseLoupeAnimation:]_block_invoke+89>
<+[UIView(UIViewAnimationWithBlocksPrivate) _modifyAnimationsWithPreferredFrameRateRange:updateReason:animations:]+166>
<block_destroy_helper.269+92>
<block_destroy_helper.269+92>
<__swift_instantiateConcreteTypeFromMangledName+94289>
<block_destroy_helper.269+126>
<+[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:anima
<block_destroy_helper.269+6763>
<block_destroy_helper.269+10907>
<-[_UITextMagnifiedLoupeView _updateCloseLoupeAnimation:]+389>
<-[_UITextMagnifiedLoupeView setVisible:animated:completion:]+256>
<-[UITextLoupeSession _invalidateAnimated:]+329>
<-[UITextRefinementTouchBehavior textLoupeInteraction:gestureChangedWithState:location:translation:velocity:
<-[UITextRefinementInteraction loupeGestureWithState:location:translation:velocity:modifierFlags:shouldCanc
<-[UITextRefinementInteraction loupeGesture:]+701>
<-[UIGestureRecognizerTarget _sendActionWithGestureRecognizer:]+71>
<_UIGestureRecognizerSendTargetActions+100>
<_UIGestureRecognizerSendActions+306>
<-[UIGestureRecognizer _updateGestureForActiveEvents]+704>
<_UIGestureEnvironmentUpdate+3892>
<-[UIGestureEnvironment _updateForEvent:window:]+847>
<-[UIWindow sendEvent:]+4937>
<-[UIApplication sendEvent:]+525>
<__dispatchPreprocessedEventFromEventQueue+1436>
<__processEventQueue+8610>
<updateCycleEntry+151>
<_UIUpdateSequenceRun+55>
<schedulerStepScheduledMainSection+165>
<runloopSourceCallback+68>
<__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__+17>
<__CFRunLoopDoSource0+157>
<__CFRunLoopDoSources0+293>
<__CFRunLoopRun+960>
<CFRunLoopRunSpecific+550>
<GSEventRunModal+137>
<-[UIApplication _run]+875>
<UIApplicationMain+123>
<__debug_main_executable_dylib_entry_point+63>
10d702478 204e57345
Type: Error | Timestamp: 2025-03-09 00:22:46.121407+09:00 | Process: FurusatoLocalCurrency | Library: CoreGraphics | Subsystem: com.apple.coregraphics | Category: Unknown process name | TID: 0x5c360
Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x600002202a30 h=--& v=--& _UIToolbarContentView:0x7fc2c6a5b8f0.width == 0 (active)>",
"<NSLayoutConstraint:0x600002175e00 H:|-(0)-[_UIButtonBarStackView:0x7fc2c6817b10] (active, names: '|':_UIToolbarContentView:0x7fc2c6a5b8f0 )>",
"<NSLayoutConstraint:0x600002175e50 H:[_UIButtonBarStackView:0x7fc2c6817b10]-(0)-| (active, names: '|':_UIToolbarContentView:0x7fc2c6a5b8f0 )>",
"<NSLayoutConstraint:0x6000022019f0 'TB_Leading_Leading' H:|-(8)-[_UIModernBarButton:0x7fc2a5aa8920] (active, names: '|':_UIButtonBarButton:0x7fc2a5aa84d0 )>",
"<NSLayoutConstraint:0x600002201a40 'TB_Trailing_Trailing' H:[_UIModernBarButton:0x7fc2a5aa8920]-(0)-| (active, names: '|':_UIButtonBarButton:0x7fc2a5aa84d0 )>",
"<NSLayoutConstraint:0x600002201e50 'UISV-canvas-connection' UILayoutGuide:0x600003b7d420'UIViewLayoutMarginsGuide'.leading == _UIButtonBarButton:0x7fc2f57117f0.leading (active)>",
"<NSLayoutConstraint:0x600002201ea0 'UISV-canvas-connection' UILayoutGuide:0x600003b7d420'UIViewLayoutMarginsGuide'.trailing == UIView:0x7fc2a5aac8e0.trailing (active)>",
"<NSLayoutConstraint:0x6000022021c0 'UISV-spacing' H:[_UIButtonBarButton:0x7fc2f57117f0]-(0)-[UIView:0x7fc2a5aa8330] (active)>",
"<NSLayoutConstraint:0x600002202210 'UISV-spacing' H:[UIView:0x7fc2a5aa8330]-(0)-[_UIButtonBarButton:0x7fc2a5aa84d0] (active)>",
"<NSLayoutConstraint:0x600002202260 'UISV-spacing' H:[_UIButtonBarButton:0x7fc2a5aa84d0]-(0)-[UIView:0x7fc2a5aac8e0] (active)>",
"<NSLayoutConstraint:0x600002176f30 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x600003b7d420'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':_UIButtonBarStackView:0x7fc2c6817b10 )>",
"<NSLayoutConstraint:0x600002176e40 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600003b7d420'UIViewLayoutMarginsGuide']-(0)-|(LTR) (active, names: '|':_UIButtonBarStackView:0x7fc2c6817b10 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600002201a40 'TB_Trailing_Trailing' H:[_UIModernBarButton:0x7fc2a5aa8920]-(0)-| (active, names: '|':_UIButtonBarButton:0x7fc2a5aa84d0 )>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
when I implementation the UNUserNotificationCenterDelegate
func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
var status = ""
if (UIApplication.shared.applicationState == .active) {
status = "active"
} else if (UIApplication.shared.applicationState == .background) {
status = "background"
} else if (UIApplication.shared.applicationState == .inactive) {
status = "inactive"
}
completionHandler()
}
I find that UIApplication.shared.applicationState == .background this case can not execute when application is in background。
why applicationState is inactive not background?
I have a UITextField in my application, and I want to detect all the keys uniquely to perform all relevant task. However, there is some problem in cleanly identifying some of the keys.
I m not able to identify the backspace key press in the textField(_:shouldChangeCharactersIn:replacementString:) method.
Also I don't know how to detect the Caps Lock key.
I am intending to so this because I want to perform some custom handling for some keys. Can someone help me with what is the way of detecting it under the recommendation from apple. Thanks in advance.
Note: checking for replacementString parameter in shouldChangeCharactersIn method for empty does not help for backspace detection as it overlaps with other cases.
I have a situation where I need to add a UINavigationController as a child view controller within another view controller. When I do this, there is a gap between the bottom of the navigation controller's root view controller and the bottom of the navigation controller's own view. This happens even though I am constraining the navigation controller's view to the edges of its superview, not the safe areas.
I'd really like to eliminate this gap, but nothing I have tried is working.
VoiceOver reads out all visible content on the screen, which is essential for visually challenged users. However, this raises a privacy concern—what if a user accidentally focuses on sensitive information, like a bank account password, and it gets read aloud?
How can developers prevent VoiceOver from exposing confidential data while still maintaining accessibility? Are there best practices or recommended approaches to handle such scenarios effectively?