Swift 3：如何缩放和旋转UIImageView？

Question

我真的很难在网上找到教程以及已经回答的问题（我试过了，但它们似乎不起作用）。我有一个位于视图中心的 UIImageView。我目前可以在屏幕上任意位置点击并拖动它。我希望能够缩放和旋转此视图。我如何实现这一目标？我已经尝试了下面的旋转代码，但它似乎不起作用？任何帮助都将是巨大的帮助并标记为答案。谢谢大家。

    import UIKit

class DraggableImage: UIImageView {

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

        self.backgroundColor = .blue

    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

        self.backgroundColor = .green

    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        if let touch = touches.first {
            let position = touch.location(in: superview)
            center = CGPoint(x: position.x, y: position.y)
        }
    }

}

class CVController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white

        let rotateGesture = UIRotationGestureRecognizer(target: self, action: #selector(rotateAction(sender:)))
        firstImageView.addGestureRecognizer(rotateGesture)

        setupViews()
    }

    func rotateAction(sender: UIRotationGestureRecognizer) {
        let rotatePoint = sender.location(in: view)
        let firstImageView = view.hitTest(rotatePoint, with: nil)
        firstImageView?.transform = (firstImageView?.transform.rotated(by: sender.rotation))!
        sender.rotation = 0
    }

    let firstImageView: DraggableImage = {
        let iv = DraggableImage()
        iv.backgroundColor = .red
        iv.isUserInteractionEnabled = true
        return iv
    }()

    func setupViews() {
        view.addSubview(firstImageView)

        let firstImageWidth: CGFloat = 50
        let firstImageHeight: CGFloat = 50

        firstImageView.frame = CGRect(x: (view.frame.width / 2) - firstImageWidth / 2, y: (view.frame.height / 2) - firstImageWidth / 2, width: firstImageWidth, height: firstImageHeight)
    }

}

Answer 1

您的代码有一些问题。首先，您需要将 UIGestureRecognizerDelegate 添加到您的视图控制器并使其成为您的手势识别器委托。您还需要实现 shouldRecognizeSimultaneously 方法和 return true。其次，在应用缩放时，您需要在捏合开始时保存变换并在其顶部应用缩放：

class DraggableImageView: UIImageView {
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        backgroundColor = .blue
    }
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        backgroundColor = .green
    }
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        if let position = touches.first?.location(in: superview){
            center = position
        }
    }
}

class ViewController: UIViewController, UIGestureRecognizerDelegate {
    
    var identity = CGAffineTransform.identity
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white
        setupViews()
        
        let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(scale))
        let rotationGesture = UIRotationGestureRecognizer(target: self, action: #selector(rotate))
        
        pinchGesture.delegate = self
        rotationGesture.delegate = self

        view.addGestureRecognizer(pinchGesture)
        view.addGestureRecognizer(rotationGesture)
    }
    let firstImageView: DraggableImageView = {
        let iv = DraggableImageView()
        iv.backgroundColor = .red
        iv.isUserInteractionEnabled = true
        return iv
    }()
    
    func setupViews() {
        view.addSubview(firstImageView)
        let firstImageWidth: CGFloat = 50
        let firstImageHeight: CGFloat = 50
        firstImageView.frame = CGRect(x: view.frame.midX - firstImageWidth / 2, y: view.frame.midY - firstImageWidth / 2, width: firstImageWidth, height: firstImageHeight)
    }
    @objc func scale(_ gesture: UIPinchGestureRecognizer) {
        switch gesture.state {
        case .began:
            identity = firstImageView.transform
        case .changed,.ended:
            firstImageView.transform = identity.scaledBy(x: gesture.scale, y: gesture.scale)
        case .cancelled:
            break
        default:
            break
        }
    }
    @objc func rotate(_ gesture: UIRotationGestureRecognizer) {
        firstImageView.transform = firstImageView.transform.rotated(by: gesture.rotation)
    }
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
}

Swift 3：如何缩放和旋转UIImageView？

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