由夹点和平移手势识别器同时触发的交互式ViewController转换

Question

我有两个viewControllers:

ViewController1

一组复杂的子视图控制器,中间有一个imageView

ViewController2

包含imageView的scrollView

我想要实现的是两个viewControllers之间的转换,它通过从viewController 1捏合imageView来触发,使其放大并切换到viewController 2.当转换结束时,imageView应该放大到目前为止因为它在捏合手势触发过渡期间被缩放.

同时我想支持在执行缩放转换时平移图像,这样就像缩放一样,处于结束状态的图像将被转换到它被平移到的位置.

到目前为止,我已经尝试过Hero过渡pod和我自己编写的自定义viewController过渡.英雄转换的问题是图像没有正确地捕捉到第二个viewController中的结束状态.我对自定义viewController转换的问题是我无法同时进行缩放和平移.

有没有人知道如何在Swift中实现它？非常感谢帮助.

Answer 1

问题可以分为两个：

1. 如何在屏幕上使用平移手势实现捏合缩放和拖动imageView
2. 如何呈现一个视图控制器，其子视图之一（在 vc2 中）与呈现视图控制器中的imageView子视图（在 vc1 中）位置相同imageView

捏合手势缩放：捏合缩放更容易使用，UIScrollView因为它开箱即用，无需添加手势识别器。创建一个scrollView并添加您想要通过捏合缩放的视图作为其子视图 ( scrollView.addSubview(imageView))。不要忘记添加scrollView自身 ( view.addSubview(scrollView))。

配置scrollView's最小和最大缩放比例：scrollView.minimumZoomScale, scrollView.maximumZoomScale. 设置委托scrollView.delegate并实施UIScrollViewDelegate：

func viewForZooming(in scrollView: UIScrollView) -> UIView?

imageView在这种情况下应该返回你的，

还符合UIGestureRecognizerDelegate并实施：

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool

这应该返回 true。这是让平移手势识别器与内部捏合手势识别器一起工作的关键。

平移手势拖动：只需创建一个带有目标的平移手势识别器并将其添加到您的滚动视图中scrollView.addGestureRecognizer(pan)。

处理手势：在此阶段，捏合缩放效果很好，除非您想在捏合结束时显示第二个视图控制器。实现另一种UIScrollViewDelegate在缩放结束时收到通知的方法：

func scrollViewDidEndZooming(_ scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat)

并调用呈现详细视图控制器的方法presentDetail()，我们稍后将实现它。

下一步是处理平移手势，我将让代码自行解释：

// NOTE: Do NOT set from anywhere else than pan handler.
private var initialTouchPositionY: CGFloat = 0
private var initialTouchPositionX: CGFloat = 0

@objc func panned(_ pan: UIPanGestureRecognizer) {

    let y = pan.location(in: scrollView).y
    let x = pan.location(in: scrollView).x

    switch pan.state {
    case .began:
        initialTouchPositionY = pan.location(in: imageView).y
        initialTouchPositionX = pan.location(in: imageView).x
    case .changed:
        let offsetY = y - initialTouchPositionY
        let offsetX = x - initialTouchPositionX
        imageView.frame.origin = CGPoint(x: offsetX, y: offsetY)
    case .ended:
        presentDetail()
    default: break
    }
}

该实现会imageView跟随平移位置移动，并presentDetail()在手势结束时调用。

在我们实现之前presentDetail()，请前往详细视图控制器并添加要保存的属性imageViewFrame及其image本身。现在在vc1中，我们presentDetail()这样实现：

private func presentDetail() {
    let frame = view.convert(imageView.frame, from: scrollView)
    let detail = DetailViewController()
    detail.imageViewFrame = frame
    detail.image = imageView.image

    // Note that we do not need the animation. 
    present(detail, animated: false, completion: nil)
}

在您的 中DetailViewController，请确保imageViewFrame在eg 中设置 和图像viewDidLoad，然后您就可以设置了。

完整的工作示例：

class ViewController: UIViewController, UIScrollViewDelegate, UIGestureRecognizerDelegate {

    let imageView: UIImageView = UIImageView()
    let scrollView: UIScrollView = UIScrollView()

    lazy var pan: UIPanGestureRecognizer = {
        return UIPanGestureRecognizer(target: self, action: #selector(panned(_:)))
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        imageView.image = // set your image

        scrollView.delegate = self
        scrollView.minimumZoomScale = 1.0
        scrollView.maximumZoomScale = 10.0

        scrollView.addSubview(imageView)
        view.addSubview(scrollView)

        scrollView.frame = view.frame

        let w = view.bounds.width - 30 // padding of 15 on each side
        imageView.frame = CGRect(x: 0, y: 0, width: w, height: w)
        imageView.center = scrollView.center

        scrollView.addGestureRecognizer(pan)
    }

    // NOTE: Do NOT set from anywhere else than pan handler.
    private var initialTouchPositionY: CGFloat = 0
    private var initialTouchPositionX: CGFloat = 0

    @objc func panned(_ pan: UIPanGestureRecognizer) {

        let y = pan.location(in: scrollView).y
        let x = pan.location(in: scrollView).x

        switch pan.state {
        case .began:
            initialTouchPositionY = pan.location(in: imageView).y
            initialTouchPositionX = pan.location(in: imageView).x
        case .changed:
            let offsetY = y - initialTouchPositionY
            let offsetX = x - initialTouchPositionX
            imageView.frame.origin = CGPoint(x: offsetX, y: offsetY)
        case .ended:
            presentDetail()
        default: break
        }
    }

    // MARK: UIScrollViewDelegate

    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        return imageView
    }

    func scrollViewDidEndZooming(_ scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
        presentDetail()
    }

    // MARK: UIGestureRecognizerDelegate

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }

    // MARK: Private

    private func presentDetail() {
        let frame = view.convert(imageView.frame, from: scrollView)
        let detail = DetailViewController()
        detail.imageViewFrame = frame
        detail.image = imageView.image
        present(detail, animated: false, completion: nil)
    }
}

class DetailViewController: UIViewController {

    let imageView: UIImageView = UIImageView()
    var imageViewFrame: CGRect!
    var image: UIImage?

    override func viewDidLoad() {
        super.viewDidLoad()
        imageView.frame = imageViewFrame
        imageView.image = image

        view.addSubview(imageView)
        view.addSubview(backButton)
    }

    lazy var backButton: UIButton = {
        let button: UIButton = UIButton(frame: CGRect(x: 10, y: 30, width: 60, height: 30))
        button.addTarget(self, action: #selector(back(_:)), for: .touchUpInside)
        button.setTitle("back", for: .normal)
        return button
    }()

    @objc func back(_ sender: UIButton) {
        dismiss(animated: false, completion: nil)
    }

}