Swift: 实现可拖拽的UIImageView需要哪些方法？

Question

如标题所述，我希望用户能够拖动用作图片图钉的 UIImageView，我已遵循 this 教程。这是我写的class：

import UIKit

class PinImageView: UIImageView {

var lastLocation:CGPoint?
var panRecognizer:UIPanGestureRecognizer?

init(imageIcon: UIImage?, location:CGPoint) {
    super.init(image: imageIcon)
    self.lastLocation = location
    self.panRecognizer = UIPanGestureRecognizer(target:self, action:"detectPan:")
    self.center = location
    self.gestureRecognizers = [panRecognizer!]
    self.frame = CGRect(x: location.x, y: location.y, width: 20.0, height: 30.0)
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

func detectPan(recognizer:UIPanGestureRecognizer) {
    let translation  = recognizer.translationInView(self.superview!)
    self.center = CGPointMake(lastLocation!.x + translation.x, lastLocation!.y + translation.y)
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    // Promote the touched view
    self.superview?.bringSubviewToFront(self)

    // Remember original location
    lastLocation = self.center
}

}

那些引脚 UIImageViews 应该移动到更大的 UIImageView 上，它包含在 UIViewController 中：

class PhotoViewController: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate {

@IBOutlet weak var imageView: UIImageView!
var imagePicker: UIImagePickerController!
var redLocationA:PinImageView = PinImageView(imageIcon: UIImage(named: "pin1.png"), location: CGPointMake(80, 330))
var redLocationB:PinImageView = PinImageView(imageIcon: UIImage(named: "pin1.png"), location: CGPointMake(80, 360))

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.addSubview(redLocationA)
    self.view.addSubview(redLocationB)
}

...
}

当我启动应用程序时，一切都正确显示，但如果我尝试拖动图钉，它们不会移动。恐怕我错过了什么……你知道吗？也许是方法 touchedìsMoved() 但教程中没有提到...

Answer 1

更新：回答

愚蠢的我，我错过了

self.userInteractionEnabled = true

在 init() 方法中，我认为它们是默认启用的。

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