On Mac, SwiftUI's .onHover closure is not always called on mouse exit, particularly with high cursor velocity. A grid of targets or with finer target shapes will often have multiple targets falsely active after the mouse has moved on.
It is easy to run back to AppKit's safety. Below is a SwiftUI-like modifier for reliable mouse-tracking. You can easily adapt it for other mouse tracking needs.
import SwiftUI
| /// MIT License | |
| /// | |
| /// Copyright (c) 2021 Lukas Kubanek, Structured Path GmbH | |
| /// | |
| /// Permission is hereby granted, free of charge, to any person obtaining a copy | |
| /// of this software and associated documentation files (the "Software"), to deal | |
| /// in the Software without restriction, including without limitation the rights | |
| /// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
| /// copies of the Software, and to permit persons to whom the Software is | |
| /// furnished to do so, subject to the following conditions: |
| import Cocoa | |
| import Foundation | |
| var colors: [NSColor] = [.labelColor, .secondaryLabelColor, .tertiaryLabelColor, .quaternaryLabelColor, .textColor, .placeholderTextColor, .selectedTextColor, .textBackgroundColor, .selectedTextBackgroundColor, .keyboardFocusIndicatorColor, .unemphasizedSelectedTextColor, .unemphasizedSelectedTextBackgroundColor, .linkColor, .separatorColor, .selectedContentBackgroundColor, .unemphasizedSelectedContentBackgroundColor, .selectedMenuItemTextColor, .gridColor, .headerTextColor, .controlAccentColor, .controlColor, .controlBackgroundColor, .controlTextColor, .disabledControlTextColor, .selectedControlColor, .selectedControlTextColor, .alternateSelectedControlTextColor, .windowBackgroundColor, .windowFrameTextColor, .underPageBackgroundColor, .findHighlightColor, .highlightColor, .shadowColor | |
| ] | |
| for color in colors { | |
| var red: CGFloat = 0 | |
| var green: CGFloat = 0 | |
| var blue: CGFloat = 0 |
| // Copyright (C) 2025 Gwendal Roué | |
| // | |
| // Permission is hereby granted, free of charge, to any person obtaining a | |
| // copy of this software and associated documentation files (the | |
| // "Software"), to deal in the Software without restriction, including | |
| // without limitation the rights to use, copy, modify, merge, publish, | |
| // distribute, sublicense, and/or sell copies of the Software, and to permit | |
| // persons to whom the Software is furnished to do so, subject to the | |
| // following conditions: | |
| // |
| #if DEBUG | |
| struct DebugFrameModifier: ViewModifier { | |
| let color = Color.red | |
| let lineWidth = 0.5 | |
| let spacing: CGFloat = 16 | |
| func body(content: Content) -> some View { | |
| content | |
| .border(color) | |
| .overlay( |