ios - 如何在 swift 3.0 中拖动和缩放 UIView 内的 UIImageView ？

Question

我想使用 swift 3.0 在 UIView 中而不是在 UIViewController (self.view) 中拖动和缩放 UIImageView。

这里我声明了mainView和imageView，

var lastScale: CGFloat = 0.0
@IBOutlet var mainView: UIView!
@IBOutlet var imageView: UIImageView!

我已经在 mainView 中设置了平移和捏合手势来缩放和拖动 ImageView

let pinchGestureRecognizer = UIPinchGestureRecognizer(target: self, action: #selector(ViewController.handlePinchGesture(_:)))
    imageView.isUserInteractionEnabled = true
    imageView.addGestureRecognizer(pinchGestureRecognizer)

let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(ViewController.handlePanGesture(recognizer:)))
    imageView.addGestureRecognizer(panGestureRecognizer)

平移和捏合手势功能

func handlePinchGesture(_ gestureRecognizer: UIPinchGestureRecognizer) {
    if gestureRecognizer.state == .began {
        lastScale = gestureRecognizer.scale
    }

    if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
        let currentScale: CGFloat = (gestureRecognizer.view!.layer.value(forKeyPath: "transform.scale")! as! CGFloat)

        // Constants to adjust the max/min values of zoom
        //let kMaxScale: CGFloat = 2.0
        let kMinScale: CGFloat = 1.0

        var newScale: CGFloat = 1 - (lastScale - gestureRecognizer.scale)

        //newScale = min(newScale, kMaxScale / currentScale)
        newScale = max(newScale, kMinScale / currentScale)

        let transform = gestureRecognizer.view?.transform.scaledBy(x: newScale, y: newScale)
        gestureRecognizer.view?.transform = transform!

        lastScale = gestureRecognizer.scale
    }
}

func handlePanGesture(recognizer: UIPanGestureRecognizer) {
    let translation = recognizer.translation(in: mainView)
    var recognizerFrame = recognizer.view?.frame
    recognizerFrame?.origin.x += translation.x
    recognizerFrame?.origin.y += translation.y
    // Check if UIImageView is completely inside its superView
    if mainView.bounds.contains(recognizerFrame!) {
        recognizer.view?.frame = recognizerFrame!
    }
    else {
        // Check vertically
        if (recognizerFrame?.origin.y)! < mainView.bounds.origin.y {
            recognizerFrame?.origin.y = 0
        }
        else if (recognizerFrame?.origin.y)! + (recognizerFrame?.size.height)! > mainView.bounds.size.height {
            recognizerFrame?.origin.y = mainView.bounds.size.height - (recognizerFrame?.size.height)!
        }

        // Check horizantally
        if (recognizerFrame?.origin.x)! < mainView.bounds.origin.x {
            recognizerFrame?.origin.x = 0
        }
        else if (recognizerFrame?.origin.x)! + (recognizerFrame?.size.width)! > mainView.bounds.size.width {
            recognizerFrame?.origin.x = mainView.bounds.size.width - (recognizerFrame?.size.width)!
        }
    }

    // Reset translation so that on next pan recognition
    // we get correct translation value
    recognizer.setTranslation(CGPoint(x: CGFloat(0), y: CGFloat(0)), in: mainView)
}

当我运行此代码时，我缩放 imageView，它超出了 mainView。那么，我该如何解决？

Answer 1

每当您缩放 subview 或移动 subview 时，都需要更改 subview 的帧值。因为frame是UIView的一个属性，所以你可以使用KVO来观察它并为其变化设置一些规则，就像你对平移所做的那样。

对于frame的KVO，可以在here找到更好的解释