NSTrackingArea(监视区域)监听鼠标的移入/内部移动/移出事件

要响应鼠标的mouseEntered、mouseExited、mouseMoved回调方法，需要为对应的NSView实例添加上NSTrackingArea(监视区域)~

如下代码，将NSTrackingArea(监视区域)添加到了self.view上：

import Cocoa

class ViewController: NSViewController {
    var kb_V: NSView?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do view setup here.
        
        self.view.wantsLayer = true
        self.view.layer?.backgroundColor = NSColor.purple.cgColor
        
        kb_V = NSView(frame: NSMakeRect(100, 100, 300, 300))
        self.view .addSubview(kb_V!)
        kb_V!.wantsLayer = true
        kb_V!.layer?.backgroundColor = NSColor.cyan.cgColor
        
        
        //添加——追踪‘鼠标’的区域
        //【一】通过枚举项的原始值`rawValue`来通过“|”或运算，得到新的NSTrackingArea.Options来使用
        let opt = (
            NSTrackingArea.Options.mouseEnteredAndExited.rawValue |
                NSTrackingArea.Options.mouseMoved.rawValue |
                NSTrackingArea.Options.activeAlways.rawValue
        )
        let trackingArea = NSTrackingArea(rect: kb_V!.frame, options: NSTrackingArea.Options(rawValue: opt), owner:self, userInfo: nil)
        self.view .addTrackingArea(trackingArea)
//        //【二】通过枚举项合成一个数组，作为NSTrackingArea.Options来使用
//        let trackingArea = NSTrackingArea(rect: kb_V!.frame, options: [NSTrackingArea.Options.mouseEnteredAndExited, NSTrackingArea.Options.mouseMoved, NSTrackingArea.Options.activeAlways], owner:self, userInfo: nil)
//        self.view .addTrackingArea(trackingArea)
        
    }
    
    //MARK:Mouse鼠标的响应
    override func mouseMoved(with event: NSEvent) {
        //event.type——判断鼠标的操作、event.locationInWindow——获取鼠标的位置
        let eventType = event.type
        let locPoint = event.locationInWindow
        print("eventType:\(eventType.rawValue),locPoint:\(locPoint)")//eventType.rawValue为5
    }
    override func mouseEntered(with event: NSEvent) {
        //event.type——判断鼠标的操作、event.locationInWindow——获取鼠标的位置
        let eventType = event.type
        let locPoint = event.locationInWindow
        print("eventType:\(eventType.rawValue),locPoint:\(locPoint)")//eventType.rawValue为8
        kb_V?.layer?.backgroundColor = NSColor.brown.cgColor    //颜色改为棕色
    }
    override func mouseExited(with event: NSEvent) {
        //event.type——判断鼠标的操作、event.locationInWindow——获取鼠标的位置
        let eventType = event.type
        let locPoint = event.locationInWindow
        print("eventType:\(eventType.rawValue),locPoint:\(locPoint)")//eventType.rawValue为9
        kb_V?.layer?.backgroundColor = NSColor.cyan.cgColor     //颜色改回青色
    }
    
}

效果：a.当鼠标移入到NSTrackingArea(监视区域)的范围时，打印event.type为8和(该时刻)鼠标的位置—颜色改为棕色、b.当鼠标在NSTrackingArea(监视区域)的范围内进行移动时，打印event.type为5和鼠标的位置、c.当鼠标移出 NSTrackingArea(监视区域)的范围时，打印event.type为9和(该时刻)鼠标的位置—颜色改回青色！

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其他更多鼠标/键盘事件的监听，可参考《Mac 鼠标/键盘事件的监听和模拟》

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