Swift 3:如何缩小和缩放UIImageView? [英] Swift 3: How do I pinch to scale and rotate UIImageView?

问题描述

我真的很难在网上找到教程以及已经回答的问题(我已经尝试过了，但是它们似乎没有用).我的视图中心有一个UIImageView.目前，我可以在屏幕上的任意位置点击并拖动它.我希望能够捏按比例缩放和旋转该视图.我该如何实现?我已经尝试了下面的旋转代码，但似乎没有用?任何帮助都是巨大的帮助，并标记为答案.谢谢你们.

I am really struggling to find tutorials online as well as already answered questions (I have tried them and they don't seem to work). I have a UIImageView that I have in the centre of my view. I am currently able to tap and drag this wherever I want on screen. I want to be able to pinch to scale and rotate this view. How do I achieve this? I have tried the code for rotation below but it doesn't seem to work? Any help will be a massive help and marked as answer. Thank you guys.

    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)
    }

}

推荐答案

您的代码中有一些问题.首先，您需要将UIGestureRecognizerDelegate添加到视图控制器，并使它成为手势识别器委托.并添加shouldRecognizeSimultaneously方法并返回true.其次，在应用缩放比例时，您需要在收缩开始时保存转换并将缩放比例应用在其顶部:

You have a some problems in your code. First you need to add the UIGestureRecognizerDelegate to your view controller and make it your gesture recognizer delegate. and add the shouldRecognizeSimultaneously method and return true. Second when applying the scale you need to save the transform when the pinch begins and apply the scale in top of it:

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
    }
}

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