John Siracusa siracusa

When creating and using a custom ButtonStyle for a SwiftUI button that changes its appearance based on the value of the configuration.isPressed property, that property sometimes get stuck with a "true" value, leaving the button to appear in its pressed state even when it is not being pressed. It stays stuck this way until the button is clicked again.

A sample project is attached. It's also in a public repo at https://github.com/siracusa/SwiftUIButtonIsPressedStateBug

To reproduce the bug:

Build and launch the sample project. A window should appear showing a large button view with a green background and some white text that says "Hello".
Click button view a few times and confirm that background color turns blue on mouse-down and switches back to green on mouse-up.

From Jonathan Dietz, Jr.:

Almost all new displays employ VESA Coordinated Video Timings using Reduced Blanking Timing Version 2 (CVT-RBv2) which adds a small amount of overhead to the video signal. This overhead includes 80 additional horizontal pixels and enough additional lines to meet the 460 µs minimum vertical blanking interval requirement. You can download an Excel spreadsheet from VESA that will do all the calculations for you, but the math is pretty simple:

460 / ((1000000 / [refresh rate in Hz] - 460) / [vertical resolution])

To get an integer number of lines, you round this result down and add 1. So for Pro Display XDR resolution at 120 Hz that would work out to:

460 / (1000000 / 120 - 460) / 3384) = 197.710 = 198 additional lines

	NSWorkspace.shared.notificationCenter.addObserver(
	forName: NSWorkspace.didLaunchApplicationNotification,
	object: nil, queue: nil, using: { [weak self] notification in

	self?.doStuff()
	})

	<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
	<plist version="1.0">
	<dict>
	<key>BreakpadProduct</key>
	<string>VLC</string>
	<key>BreakpadRequestComments</key>
	<string>1</string>
	<key>BreakpadURL</key>
	<string>https://mac.crashes.videolan.org/reports</string>

	import Cocoa
	import Observation

	@Observable
	class User {
	@ObservationIgnored lazy var id : Int = {
	return Int.random(in: 1...100)
	}()
	}

	import Cocoa
	import Observation

	//@Observable
	class User {
	// If @Observable is applied to this class, compilation
	// of this property declaration fails with the error:
	//
	// 'lazy' cannot be used on a computed property
	//

	extension View {
	@ViewBuilder
	func `if`<Content: View>(_ conditional: Bool, @ViewBuilder content: (Self) -> Content) -> some View {
	if conditional {
	content(self)
	}
	else {
	self
	}
	}

	Sampling process 2517 for 3 seconds with 1 millisecond of run time between samples
	Sampling completed, processing symbols...
	Analysis of sampling Safari (pid 2517) every 1 millisecond
	Process: Safari [2517]
	Path: /Applications/Safari.app/Contents/MacOS/Safari
	Load Address: 0x10a637000
	Identifier: com.apple.Safari
	Version: 15.0 (15612.1.29.41.4)
	Build Info: Safari-7612001029041004~7
	Code Type: X86-64

	579 => Blessed System File is /System/Volumes/Preboot/B24F40F6-A709-475D-8FE9-0BC32E6BA240/System/Library/CoreServices/boot.efi
	366 => Blessed System Folder is /System/Volumes/Preboot/B24F40F6-A709-475D-8FE9-0BC32E6BA240/System/Library/CoreServices
	The blessed volume in this APFS container is "/".
	The blessed APFS snapshot for this volume is "3E14543D-BE61-487B-B49A-2AF55563C403".