1. 监听全局键盘事件

在macOS开发中，我们时常会有一些要监听鼠标或者键盘全局事件的需求， 比如按下option键，显示view

代码：

- (void)awakeFromNib
{[super awakeFromNib];if (self) {__weak typeof(self) weakSelf = self;self.globalEventMonitor = [NSEvent addGlobalMonitorForEventsMatchingMask:NSEventMaskFlagsChanged handler:^(NSEvent * _Nonnull event) {NSLog(@"Victor-Debug:  Global");
//           [NSEvent removeMonitor:weakSelf.globalEventMonitor];}];self.localEventMonitor = [NSEvent addLocalMonitorForEventsMatchingMask:NSEventMaskFlagsChanged handler:^NSEvent * _Nullable(NSEvent * event) {NSLog(@"Victor-Debug:  Local");
//            [NSEvent removeMonitor:weakSelf.localEventMonitor];return event;}];}
}- (void)dealloc
{[NSEvent removeMonitor:self.localEventMonitor];[NSEvent removeMonitor:self.globalEventMonitor];
}

在系统中加入一个回调，根据参数条件执行block.

• 最后要注意移除监视器

2. 判断鼠标是否按下

1). 在NSView中添加flag: isMouseDown

在下面的API中设置flag值

- (void)mouseDown:(NSEvent *)event;
- (void)rightMouseDown:(NSEvent *)event;
- (void)otherMouseDown:(NSEvent *)event;
- (void)mouseUp:(NSEvent *)event;
- (void)rightMouseUp:(NSEvent *)event;

2). 利用NSEvent的类变量

open class var pressedMouseButtons: Int { get }

1：鼠标左键被按下
2：鼠标右键键被按下
3：鼠标左键和右键同时被按下