Swift：NSMutableSet - ＆gt;类型'CGPoint'不符合协议'AnyObject'

Question

为什么这个代码结果为“Type'CGPoint'不符合协议'AnyObject'”？

let mutableSet = NSMutableSet()
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    /* Called when a touch begins */
    touch = touches.anyObject() as UITouch!
    mutableSet.addObject(touch.locationInNode(self))
}

Answer 1

NSMutableSet只接受引用类型，但CGPoint是结构，值类型。您可以将该点包装在NSValue中以添加它。

mutableSet.addObject(NSValue(CGPoint: touch.locationInNode(self)))