如何观察图像旋转？

Question

我有一个名为 - （woowwww）的ImageView： ImageView

@IBOutlet weak var ImageView: UIImageView!

...我想在每次ImageView的transform - 属性发生变化时触发事件。

每次ImageView被旋转时都应该调用一个事件：

self.ImageView.transform = CGAffineTransform(rotationAngle: CGFloat(10))

为了达到这个目的，我尝试使用某种 KVO ，但显然它没有按预期工作......

override func viewDidLoad() {
    super.viewDidLoad()
    self.ImageView.addObserver(self.ImageView.transform, forKeyPath: "test", options: .new, context: nil)
}


func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutableRawPointer) {
    print("changed")
}

任何帮助都将非常感谢！感谢。

Answer 1

在keyPath中设置“transform”，如下所示：

imgView.addObserver(self, forKeyPath: "transform", options: .new, context: nil)

然后添加以下代码：

 override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if let newValue = change?[.newKey] as? NSObject {

            print("Changed \(newValue)")
        }

希望它会对你有所帮助。

Answer 2

keyPath应该是nameOfObject.property所以如果imageView名称是dd来收听转换它应该是dd.transform

试试这个

class ViewController: UIViewController {

@IBOutlet weak var dd: UIImageView!
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

   self.addObserver(self, forKeyPath: "dd.transform", options: .new, context: nil)


   self.dd.transform = CGAffineTransform(rotationAngle: CGFloat(10))

}


override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if let newValue = change?[.newKey] as? NSObject {

        print("Changed \(newValue)")
    }

}}