I am observing an unexpected behavior with external keyboard input on iOS. When I press Command + key (e.g., ⌘ + J) while a UITextView is focused, the system invokes pressesBegan(_ presses: Set<UIPress>, with event: UIPressesEvent?) twice: -> Once with the key press event without any modifier flags. -> A second time with the same key event but including the Command modifier flag. This behavior is checked on an iPad with an external keyboard. Additionally, I noticed that textView(_:shouldChangeTextIn:replacementText:) is not invoked in this case, even if I call super.pressesBegan for event propagation. Questions: Is it expected that pressesBegan fires twice for a Command + key combination? If so, what is the recommended way to distinguish between these two invocations? Should the UITextView delegate methods (like shouldChangeTextIn) be triggered for such key combinations, or is this by design?

I’m trying to understand the exact role of the return value in the UITextFieldDelegate method textFieldShouldReturn(_:). From my experiments in Xcode, I observed: Returning true vs false does not seem to cause any visible difference (e.g., the keyboard does not automatically dismiss either way). I know that in shouldChangeCharactersIn returning true allows the system to insert the character, and returning false prevents it. That’s clear. For textFieldShouldReturn, my current understanding is that returning true means “let the OS handle the Return press,” and returning false means “I’ll handle it myself.” My confusion: what is it that the OS actually does when it “handles” the Return press? Does UIKit do anything beyond calling this delegate method? If the system is supposed to dismiss the keyboard when returning true, why doesn’t it happen automatically? I’d appreciate clarification on the expected use of this return value — specifically, what default behavior the system performs (if any) when we return true. Thanks!

In my SwiftUI iOS app, I need to detect which key (and modifier flags – Command, Option, Shift, Control) a user presses, but I don't want to pre-register them using .keyboardShortcut(_:modifiers:). My use case is that keyboard shortcuts are user-configurable, so I need to capture the actual key + modifier combination dynamically at runtime and perform the appropriate action based on the user’s settings. Questions: What is the recommended way to detect arbitrary key + modifier combinations in SwiftUI on iOS? Is there a SwiftUI-native solution for this, or should I rely on UIPressesEvent and wrap it with UIViewControllerRepresentable? If UIKit bridging is necessary, what is the cleanest pattern for integrating this with SwiftUI views (e.g., Buttons)? Any official guidance or best practices would be greatly appreciated!

I am building a centralized event handling system for UIKit controls and gesture recognizers. My current approach registers events using static methods inside a handler class, like this: internal class TWOSInternalCommonEventKerneliOS { internal static func RegisterTouchUpInside(_ pWidget: UIControl) -> Void { pWidget.addTarget( TWOSInternalCommonEventKerneliOS.self, action: #selector(TWOSInternalCommonEventKerneliOS.WidgetTouchUpInsideListener(_:)), for: .touchUpInside ) } @objc internal static func WidgetTouchUpInsideListener(_ pWidget: UIView) -> Void { print("WidgetTouchUpInside") } } This works in my testing because the methods are marked @objc and static, but I couldn’t find Apple documentation explicitly confirming whether using ClassName.self (instead of an object instance) is officially supported. Questions: Is this approach (passing ClassName.self as the target) recommended or officially supported by UIKit? If not, what is the safer alternative to achieve a similar pattern, where event registration can remain in static methods but still follow UIKit conventions? Would using a shared singleton instance as the target (e.g., TWOSInternalCommonEventKerneliOS.shared) be the correct approach, or is there a better pattern? Looking for official guidance to avoid undefined behavior in production.

I have a question about how UIKit expects us to handle interaction events at scale. From what I understand so far: For UIControls (UIButton, UISwitch, UITextField, etc.), we explicitly register with addTarget(_:action:for:). For gestures, we add UIGestureRecognizer instances to views. For UIView subclasses, we can override touch methods like touchesBegan/touchesEnded. All of this must be done on the main thread, since UIKit isn’t thread-safe. Now here’s my main concern If I have a complex UI with hundreds or thousands of widgets, am I expected to perform these registrations individually for each widget and each high-level event (tap, long press, editing changed, etc.)? Or does UIKit provide a more centralized mechanism? In short: Is per-widget, per-event registration the “normal” UIKit approach, or are there best practices for scaling event handling without writing thousands of addTarget or addGestureRecognizer calls? Thanks!

I’m working with UIButton and finding different examples for event handling. Currently, I have a single action method like this, which receives the sender and the UIEvent: @objc func buttonHandler(_ sender: UIButton, forEvent event: UIEvent) { if let touches = event.allTouches, let touch = touches.first { switch touch.phase { case .began: print("TouchDown") case .ended: if sender.bounds.contains(touch.location(in: sender)) { print("TouchUpInside") } else { print("TouchUpOutside") } case .cancelled: print("TouchCancel") default: break } } if event.type == .presses { print("PrimaryActionTriggered") } } Is this considered best/recommended practice in UIKit, or should I use separate selector methods for each event type (e.g. .touchDown, .touchUpInside, .touchUpOutside) using addTarget(_:action:for:)? Are there any advantages or disadvantages to using a single handler with UIEvent versus multiple selectors for UIControlEvents? Thanks in advance!

I’m working with UIButton and I’d like to register multiple UIControl.Events (e.g. .touchUpInside, .touchDown, .touchCancel, .primaryActionTriggered) using the same selector. For example: button.addTarget(self, action: #selector(handleButtonEvent(_:forEvent:)), for: [.touchUpInside, .touchDown, .touchCancel, .primaryActionTriggered]) @objc func handleButtonEvent(_ sender: UIButton, forEvent event: UIEvent) { // How do I tell which UIControl.Event triggered this? } From my understanding: If I use the single-parameter version (@objc func handleButtonEvent(_ sender: UIButton)), I can’t distinguish which event fired. If I use the two-parameter version with UIEvent, I can inspect touch.phase or event.type, but that feels indirect. Questions: Is there a recommended way to directly know which UIControl.Event caused the selector to fire? Is sharing a single selector across multiple control events considered a good practice, or is it more common to register separate selectors per event? Would appreciate guidance on what Apple recommends here.

I’m trying to detect a double-tap action on a UIButton. There seem to be two possible approaches: Using a UITapGestureRecognizer with numberOfTapsRequired = 2. Using the .touchDownRepeat event of UIControl.Event. What is the recommended approach for reliably handling double-taps on UIButton? Are there any practical differences in terms of behavior, performance, or best practices between these two methods? Additionally, I noticed that UIControl.Event defines a large set of events (like .editingChanged, .valueChanged, etc.). Can all these events be applied to any UIControl subclass such as UIButton, or are they only valid for specific controls like UITextField, UISlider, etc.? If not all events are supported by all controls, what is the rationale behind exposing them under a shared UIControl.Event enum? Thanks in advance!

In UIKit, UIButton provides a configuration property which allows us to create and customize a UIButton.Configuration instance independently (on a background thread or elsewhere) and later assign it to a UIButton instance. This separation of configuration and assignment is very useful for clean architecture and performance optimization. Questions: Is this configuration-style pattern (creating a configuration object separately and assigning it later) available or planned for other UIKit components such as UILabel, UITextField, UISlider, etc.? Similarly, in AppKit on macOS, are there any components (e.g. NSButton, NSTextField) that support a comparable configuration object mechanism that can be used the same way — constructed separately and assigned to the view later? This would help in building consistent configuration-driven UI frameworks across Apple platforms. Any insight or official guidance would be appreciated.

I'm working on an iOS app that requires an @mention system in a UITextView, similar to those in apps like Twitter or Slack. Specifically, I need to: Detect @ Symbol and Show Dropdown: When the user types "@", display a dropdown (UITableView or similar) below the cursor with a list of mentionable users, filtered as the user types. Handle Selection: Insert the selected username as a styled mention (e.g., blue text). Smart Backspace Behavior: Ensure backspace deletes an entire mention as a single unit when the cursor is at its end, and cancels the mention process if "@" is deleted. I've implemented a solution using UITextViewDelegate textViewDidChange(_:) to detect "@", a UITableView for the dropdown, and NSAttributedString for styling mentions. For smart backspace, I track mention ranges and handle deletions accordingly. However, I’d like to know: What is Apple’s recommended approach for implementing this behavior? Are there any UIKit APIs that simplify this, for proving this experience like smart backspace or custom text interactions? I’m using Swift/UIKit. Any insights, sample code, or WWDC sessions you’d recommend would be greatly appreciated! Edit: I am adding the ViewController file to demonstrate the approach that I m using. import UIKit // MARK: - Dummy user model struct MentionUser { let id: String let username: String } class ViewController: UIViewController, UITextViewDelegate, UITableViewDelegate, UITableViewDataSource { // MARK: - UI Elements private let textView = UITextView() private let mentionTableView = UITableView() // MARK: - Data private var allUsers: [MentionUser] = [...] private var filteredUsers: [MentionUser] = [] private var currentMentionRange: NSRange? // MARK: - View Lifecycle override func viewDidLoad() { super.viewDidLoad() view.backgroundColor = .white setupTextView() // to setup the UI setupDropdown() // to setup the UI } // MARK: - UITextViewDelegate func textViewDidChange(_ textView: UITextView) { let cursorPosition = textView.selectedRange.location let text = (textView.text as NSString).substring(to: cursorPosition) if let atRange = text.range(of: "@[a-zA-Z0-9_]*$", options: .regularExpression) { let nsRange = NSRange(atRange, in: text) let query = (text as NSString).substring(with: nsRange).dropFirst() currentMentionRange = nsRange filteredUsers = allUsers.filter { $0.username.lowercased().hasPrefix(query.lowercased()) } mentionTableView.reloadData() showMentionDropdown() } else { hideMentionDropdown() currentMentionRange = nil } } func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool { if text.isEmpty, let attributedText = textView.attributedText { if range.location == 0 { return true } let attr = attributedText.attributes(at: range.location - 1, effectiveRange: nil) if let _ = attr[.mentionUserId] { let fullRange = (attributedText.string as NSString).rangeOfMentionAt(location: range.location - 1) let mutable = NSMutableAttributedString(attributedString: attributedText) mutable.deleteCharacters(in: fullRange) textView.attributedText = mutable textView.selectedRange = NSRange(location: fullRange.location, length: 0) textView.typingAttributes = [ .font: textView.font ?? UIFont.systemFont(ofSize: 16), .foregroundColor: UIColor.label ] return false } } return true } // MARK: - Dropdown Visibility private func showMentionDropdown() { guard let selectedTextRange = textView.selectedTextRange else { return } mentionTableView.isHidden = false } private func hideMentionDropdown() { mentionTableView.isHidden = true } // MARK: - UITableViewDataSource func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return filteredUsers.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) cell.textLabel?.text = "@\(filteredUsers[indexPath.row].username)" return cell } // MARK: - UITableViewDelegate func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { insertMention(filteredUsers[indexPath.row]) } // MARK: - Mention Insertion private func insertMention(_ user: MentionUser) { guard let range = currentMentionRange else { return } let mentionText = "\(user.username)" let mentionAttributes: [NSAttributedString.Key: Any] = [ .foregroundColor: UIColor.systemBlue, .mentionUserId: user.id ] let mentionAttrString = NSAttributedString(string: mentionText, attributes: mentionAttributes) let mutable = NSMutableAttributedString(attributedString: textView.attributedText) mutable.replaceCharacters(in: range, with: mentionAttrString) let spaceAttr = NSAttributedString(string: " ", attributes: textView.typingAttributes) mutable.insert(spaceAttr, at: range.location + mentionText.count) textView.attributedText = mutable textView.selectedRange = NSRange(location: range.location + mentionText.count + 1, length: 0) textView.typingAttributes = [ .font: textView.font ?? UIFont.systemFont(ofSize: 16), .foregroundColor: UIColor.label ] hideMentionDropdown() } } // MARK: - Custom Attributed Key extension NSAttributedString.Key { static let mentionUserId = NSAttributedString.Key("mentionUserId") }

I'm working on a macOS application that needs to query the list of available printers using NSPrinter.printerNames. For performance reasons, I'd like to perform this operation on a background thread. However, since NSPrinter is part of AppKit, and AppKit is generally not thread-safe unless explicitly stated, I want to confirm: Is it safe to call NSPrinter.printerNames from a background thread? I couldn’t find explicit guidance in the documentation regarding the thread-safety of printerNames, so any clarification or best practices would be appreciated. Thanks in advance! Note: I tested this api on a background thread in code and it did not give any error.

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.

In a UIKit application, removing a view from the hierarchy is straightforward—we simply call myView.removeFromSuperview(). This not only removes myView from the UI but also deallocates any associated memory. Now that I'm transitioning to SwiftUI, I'm struggling to understand the recommended way to remove a view from the hierarchy, given SwiftUI's declarative nature. I understand that in SwiftUI, we declare everything that should be displayed. However, once a view is rendered, what is the correct way to remove it? Should all UI elements be conditionally controlled to determine whether they appear or not? Below is an example of how I’m currently handling this, but it doesn’t feel like the right approach for dynamically removing a view at runtime. Can someone guide me on the best way to remove views in SwiftUI? struct ContentView: View { @State private var isVisible = true var body: some View { VStack { if isVisible { // set this to false to remove TextView? Text("Hello, SwiftUI!") .padding() } Button("Toggle View") { ... } } } }

In UIKit, certain events like a button tap can be simulated using: button.sendActions(for: .touchUpInside) This allows us to trigger the button’s action programmatically. However, in SwiftUI, there is no direct equivalent of sendActions(for:) for views like Button. What is the recommended approach to programmatically simulate a SwiftUI button tap and trigger its action? Is there an alternative mechanism to achieve this(and for other events under UIControl.event) , especially in scenarios where we want to test interactions or trigger actions without direct user input?

in iOS, user can set focus on UItextField and tapping a key in the virtual keyboard updates the text in the textfield. This user action causes the relevant delegates of UITextFieldDelegate to get invoked, i.e the handlers associated with action of user entering some text in the textfield. I m trying to simulate this user action where I am trying to do this programatically. I want to simulate it in a way such that all the handlers/listeners which otherwise would have been invoked as a result of user typing in the textfield should also get invoked now when i am trying to do it programatically. I have a specific usecase of this in my application. Below is how I m performing this simulation. I m manually updating the text field associated(UITextField.text) and updating its value. And then I m invoking the delegate manually as textField.delegate?.textField?(textField, shouldChangeCharactersIn: nsRange, replacementString: replacementString) I wanted to know If this is the right way to do this. Is there something better available that can be used, such that simulation has the same affect as the user performing the update?