如何检测VoiceOver是否在MacOS中打开

Question

我正在开发一个MacOS应用程序，我不知道如何收听辅助功能状态的更改(例如，当VoiceOver打开或关闭时(。

在iOS中，有一个通知我可以收听，UIAccessibilityVoiceOverStatusDidChangeNotification。

MacOS中有类似的软件吗？

Answer 1

原来有一个隐藏的api来监听可访问性通知。您可以收听@"NSApplicationDidChangeAccessibilityEnhancedUserInterfaceNotification"

[center addObserver:self
selector:@selector(onAccessibilityStatusChanged:)
name:@"NSApplicationDidChangeAccessibilityEnhancedUserInterfaceNotification"
object:nil];

然后在该方法中，您可以检查10.13 中引入的voiceOverEnabled

if(@available(macOS 10.13, *)) {
NSWorkspace * ws = [NSWorkspace sharedWorkspace];
NSLog(@"got notification voiceover enabled ? %d",ws.voiceOverEnabled);
}

Answer 2

在macOS上，正确的方法是通过KVO:

[[NSWorkspace sharedWorkspace] addObserver:self forKeyPath:@"voiceOverEnabled" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:nil];

附带的处理程序方法：

- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context {

if ([keyPath isEqualToString:@"voiceOverEnabled"]) {
// handle the event in your way.
//
} else {
// Any unrecognized context must belong to super
[super observeValueForKeyPath:keyPath
ofObject:object
change:change
context:context];
}
}

在iOS和tvOS上，使用：

[[NSNotificationCenter defaultCenter] addObserverForName:UIAccessibilityVoiceOverStatusDidChangeNotification
object:nil
queue:nil
usingBlock:^(NSNotification * _Nonnull note) {
// handle the event in your way.
}];