问题描述
是否可以在没有引用NSEvent的情况下在Objective-C中获得键盘状态?
Is it possible to get the keyboard state in Objective-C without referring to NSEvent?
通常，我不能使用像-[NSResponder flagsChanged:]这样的NSResponder方法，但是我需要知道当前是否按下了Command键.
In general I can't use NSResponder methods like -[NSResponder flagsChanged:] but I need to know if the Command key is currently pressed.
推荐答案
我仍然想知道为什么您不能使用NSEvent，但是我还是要回答这个问题.也许您正在构建命令行工具"并且仅与Foundation链接?您将必须至少包含一个以上的框架.如果要链接到AppKit，可以(如我在评论中所述)使用 +[NSEvent modifierFlags] ;这是NSEvent上的类方法，因此您可以在任何地方使用它，而无需访问单个事件，以获取修饰键的当前状态作为位掩码.该文档解释了位掩码的含义.
I'm still wondering why you can't use NSEvent, but I'm going to answer the question anyways. Perhaps you're building a "command-line tool" and are only linked against Foundation? You're going to have to include at least one more framework. If you want to link against AppKit, you can (as I mentioned in the comments) use +[NSEvent modifierFlags]; this is a class method on NSEvent, so you can use it anywhere, without needing to have access to an individual event, to get the current state of the modifier keys as a bitmask. The docs explain the meaning of the bitmask.
if( NSCommandKeyMask & [NSEvent modifierFlags] ){
NSLog(@"Oh, yeah!");
}
您还可以使用石英事件服务.在这种情况下，您必须包括ApplicationServices框架*. CGEventSource函数将为您提供相同的位掩码，您从NSEvent获得:
You can also get this info using Quartz Event Services. In this case you have to include the ApplicationServices framework*. The CGEventSource functions will give you the same bitmask you get from NSEvent:
CGEventFlags theFlags;
theFlags = CGEventSourceFlagsState(kCGEventSourceStateHIDSystemState);
if( kCGEventFlagMaskCommand & theFlags ){
NSLog(@"Uh huh!");
}
*实际上，如果您正在编写Cocoa应用程序，则这已包括在内-它是Quartz的一部分.
*This is already included if you are, in fact, writing a Cocoa app -- it's part of Quartz.
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