像Snapchat [SWIFT 3]同时捏,平移和旋转文本

Question

我正在尝试制作一个像Snapchat一样可以移动的TextView.我做了类似的东西,虽然当你尝试旋转时进行缩放时,它往往会无限地水平拉伸,拖动有时可能会有点儿.

我有这个:

func panGesture(pan: UIPanGestureRecognizer) {
    print("Being Dragged")
    if pan.state == .began {
        textViewOrigin = pan.location(in: textView)
    }else {
        let location = pan.location(in: view) // get pan location
        textView.frame.origin = CGPoint(x: location.x - textViewOrigin.x, y: location.y - textViewOrigin.y)
    }
}
func scaleGesture(_ gesture: UIPinchGestureRecognizer){
    print("Being Scaled")
    switch gesture.state{
    case.began:
        identity = textView.transform
    case.changed,.ended:
        textView.transform = identity.scaledBy(x: gesture.scale, y: gesture.scale)
    default:
        break
    }
}
func rotationGesture(sender: UIRotationGestureRecognizer){
    print("Being Rotated")
    textView.transform = textView.transform.rotated(by: sender.rotation)
    sender.rotation = 0
}

而我正在努力实现这一目标:

如果有人可以帮助改变或重写我的代码,这将是伟大的,提前感谢!

Answer 1

默认情况下,在视图上的一个手势识别器开始处理手势后,其他识别器将被忽略.可以通过覆盖方法(对于Swift)来控制此行为:

gestureRecognizer(_:shouldRecognizeSimultaneouslyWith :)

返回真实.默认实现返回false.要覆盖该函数,只需将实现(返回true)添加到ViewController源代码文件中.

以下是一些示例Swift代码(请参阅https://developer.apple.com/documentation/uikit/uigesturerecognizerdelegate/1624208-gesturerecognizer?changes=_7):

class ViewController: UIViewController,UIGestureRecognizerDelegate {

    @IBOutlet var textField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        //add pan gesture
        let gestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
        gestureRecognizer.delegate = self
        textField.addGestureRecognizer(gestureRecognizer)

        //Enable multiple touch and user interaction for textfield
        textField.isUserInteractionEnabled = true
        textField.isMultipleTouchEnabled = true

        //add pinch gesture
        let pinchGesture = UIPinchGestureRecognizer(target: self, action:#selector(pinchRecognized(pinch:)))
        pinchGesture.delegate = self
        textField.addGestureRecognizer(pinchGesture)

        //add rotate gesture.
        let rotate = UIRotationGestureRecognizer.init(target: self, action: #selector(handleRotate(recognizer:)))
        rotate.delegate = self
        textField.addGestureRecognizer(rotate)


    }

    func handlePan(_ gestureRecognizer: UIPanGestureRecognizer) {
        if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {

            let translation = gestureRecognizer.translation(in: self.view)
            // note: 'view' is optional and need to be unwrapped
            gestureRecognizer.view!.center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)
            gestureRecognizer.setTranslation(CGPoint.zero, in: self.view)
        }

    }

    func pinchRecognized(pinch: UIPinchGestureRecognizer) {

        if let view = pinch.view {
            view.transform = view.transform.scaledBy(x: pinch.scale, y: pinch.scale)
            pinch.scale = 1
        }
    }

    func handleRotate(recognizer : UIRotationGestureRecognizer) {
        if let view = recognizer.view {
            view.transform = view.transform.rotated(by: recognizer.rotation)
            recognizer.rotation = 0
        }
    }

    //MARK:- UIGestureRecognizerDelegate Methods
    func gestureRecognizer(_: UIGestureRecognizer,
        shouldRecognizeSimultaneouslyWith shouldRecognizeSimultaneouslyWithGestureRecognizer:UIGestureRecognizer) -> Bool {
        return true
    }
}

在Objective C中,最重要的功能就是这个(参见https://developer.apple.com/documentation/uikit/uigesturerecognizerdelegate/1624208-gesturerecognizer?language=objc):

-(BOOL)gestureRecognizer:(UIGestureRecognizer*)aR1 shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)aR2
    {
    return YES;
    }

Answer 2

我写了一个易于使用的类。

基本用法：

// define 
var snapGesture: SnapGesture?

// add gesture
self.snapGesture = SnapGesture(view: self.testView!)

// remove gesture
self.snapGesture = nil

高级用法，对于视图接收手势为背景视图的场景：

// add gesture
self.snapGesture = SnapGesture(transformView: self.testView!, gestureView: self.view)

// remove gesture
self.snapGesture = nil

班级：

import UIKit

/*
 usage:

    add gesture:
        yourObjToStoreMe.snapGesture = SnapGesture(view: your_view)
    remove gesture:
        yourObjToStoreMe.snapGesture = nil
    disable gesture:
        yourObjToStoreMe.snapGesture.isGestureEnabled = false
    advanced usage:
        view to receive gesture(usually superview) is different from view to be transformed,
        thus you can zoom the view even if it is too small to be touched.
        yourObjToStoreMe.snapGesture = SnapGesture(transformView: your_view_to_transform, gestureView: your_view_to_recieve_gesture)

 */

class SnapGesture: NSObject, UIGestureRecognizerDelegate {

    // MARK: - init and deinit
    convenience init(view: UIView) {
        self.init(transformView: view, gestureView: view)
    }
    init(transformView: UIView, gestureView: UIView) {
        super.init()

        self.addGestures(v: gestureView)
        self.weakTransformView = transformView
    }
    deinit {
        self.cleanGesture()
    }

    // MARK: - private method
    private weak var weakGestureView: UIView?
    private weak var weakTransformView: UIView?

    private var panGesture: UIPanGestureRecognizer?
    private var pinchGesture: UIPinchGestureRecognizer?
    private var rotationGesture: UIRotationGestureRecognizer?

    private func addGestures(v: UIView) {

        panGesture = UIPanGestureRecognizer(target: self, action: #selector(panProcess(_:)))
        v.isUserInteractionEnabled = true
        panGesture?.delegate = self     // for simultaneous recog
        v.addGestureRecognizer(panGesture!)

        pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(pinchProcess(_:)))
        //view.isUserInteractionEnabled = true
        pinchGesture?.delegate = self   // for simultaneous recog
        v.addGestureRecognizer(pinchGesture!)

        rotationGesture = UIRotationGestureRecognizer(target: self, action: #selector(rotationProcess(_:)))
        rotationGesture?.delegate = self
        v.addGestureRecognizer(rotationGesture!)

        self.weakGestureView = v
    }

    private func cleanGesture() {
        if let view = self.weakGestureView {
            //for recognizer in view.gestureRecognizers ?? [] {
            //    view.removeGestureRecognizer(recognizer)
            //}
            if panGesture != nil {
                view.removeGestureRecognizer(panGesture!)
                panGesture = nil
            }
            if pinchGesture != nil {
                view.removeGestureRecognizer(pinchGesture!)
                pinchGesture = nil
            }
            if rotationGesture != nil {
                view.removeGestureRecognizer(rotationGesture!)
                rotationGesture = nil
            }
        }
        self.weakGestureView = nil
        self.weakTransformView = nil
    }




    // MARK: - API

    private func setView(view:UIView?) {
        self.setTransformView(view, gestgureView: view)
    }

    private func setTransformView(_ transformView: UIView?, gestgureView:UIView?) {
        self.cleanGesture()

        if let v = gestgureView  {
            self.addGestures(v: v)
        }
        self.weakTransformView = transformView
    }

    open func resetViewPosition() {
        UIView.animate(withDuration: 0.4) {
            self.weakTransformView?.transform = CGAffineTransform.identity
        }
    }

    open var isGestureEnabled = true

    // MARK: - gesture handle

    // location will jump when finger number change
    private var initPanFingerNumber:Int = 1
    private var isPanFingerNumberChangedInThisSession = false
    private var lastPanPoint:CGPoint = CGPoint(x: 0, y: 0)
    @objc func panProcess(_ recognizer:UIPanGestureRecognizer) {
        if isGestureEnabled {
            //guard let view = recognizer.view else { return }
            guard let view = self.weakTransformView else { return }

            // init
            if recognizer.state == .began {
                lastPanPoint = recognizer.location(in: view)
                initPanFingerNumber = recognizer.numberOfTouches
                isPanFingerNumberChangedInThisSession = false
            }

            // judge valid
            if recognizer.numberOfTouches != initPanFingerNumber {
                isPanFingerNumberChangedInThisSession = true
            }
            if isPanFingerNumberChangedInThisSession {
                return
            }

            // perform change
            let point = recognizer.location(in: view)
            view.transform = view.transform.translatedBy(x: point.x - lastPanPoint.x, y: point.y - lastPanPoint.y)
            lastPanPoint = recognizer.location(in: view)
        }
    }



    private var lastScale:CGFloat = 1.0
    private var lastPinchPoint:CGPoint = CGPoint(x: 0, y: 0)
    @objc func pinchProcess(_ recognizer:UIPinchGestureRecognizer) {
        if isGestureEnabled {
            guard let view = self.weakTransformView else { return }

            // init
            if recognizer.state == .began {
                lastScale = 1.0;
                lastPinchPoint = recognizer.location(in: view)
            }

            // judge valid
            if recognizer.numberOfTouches < 2 {
                lastPinchPoint = recognizer.location(in: view)
                return
            }

            // Scale
            let scale = 1.0 - (lastScale - recognizer.scale);
            view.transform = view.transform.scaledBy(x: scale, y: scale)
            lastScale = recognizer.scale;

            // Translate
            let point = recognizer.location(in: view)
            view.transform = view.transform.translatedBy(x: point.x - lastPinchPoint.x, y: point.y - lastPinchPoint.y)
            lastPinchPoint = recognizer.location(in: view)
        }
    }


    @objc func rotationProcess(_ recognizer: UIRotationGestureRecognizer) {
        if isGestureEnabled {
            guard let view = self.weakTransformView else { return }

            view.transform = view.transform.rotated(by: recognizer.rotation)
            recognizer.rotation = 0
        }
    }


    //MARK:- UIGestureRecognizerDelegate Methods
    func gestureRecognizer(_: UIGestureRecognizer,
                           shouldRecognizeSimultaneouslyWith shouldRecognizeSimultaneouslyWithGestureRecognizer:UIGestureRecognizer) -> Bool {
        return true
    }

}

现在，您达到了这一点，请继续。如您所知，superView 中的手势可能会吃掉子视图的事件，而在 snapchat 示例中，手势会吃掉工具栏的事件，如果我们触摸工具栏，我们需要防止来自超视图的任何手势识别。

这个想法是在工具栏上添加一个伪自定义手势，因此任何手势都将被阻止到超级视图，并且这个伪手势除了将手势或事件传递给子视图或它自己的视图之外什么都不做。

这里，我也写了一个类，方便使用。

用法：

   toolbarView.addGestureRecognizer(SnapBlockGestureRecognizer)

执行：

import UIKit

class SnapBlockGestureRecognizer: UIGestureRecognizer {

    init() {
        //self.init(target: self, action: #selector(__dummyAction))
        super.init(target: nil, action: nil)

        self.addTarget(self, action: #selector(__dummyAction))
        self.cancelsTouchesInView = false
    }

    override init(target: Any?, action: Selector?) {
        super.init(target: target, action: action)

        self.cancelsTouchesInView = false
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        if self.state == .possible {
            self.state = .began
        }
    }

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

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
        self.state = .recognized
    }

    override func canBePrevented(by preventingGestureRecognizer: UIGestureRecognizer) -> Bool {
        return self.isGestureRecognizerAllowed(gr:preventingGestureRecognizer)
    }


    override func canPrevent(_ preventedGestureRecognizer: UIGestureRecognizer) -> Bool {
        return !(self.isGestureRecognizerAllowed(gr: preventedGestureRecognizer))
    }

    override func shouldBeRequiredToFail(by otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return !(self.isGestureRecognizerAllowed(gr: otherGestureRecognizer))
    }

    override func shouldRequireFailure(of otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return false
    }

    func isGestureRecognizerAllowed(gr: UIGestureRecognizer) -> Bool {
        return gr.view!.isDescendant(of: self.view!)
    }

    @objc func __dummyAction() {
        // do nothing
        // print("dummyAction")
    }
}