拖动UIButton而不转移到中心[Swift 3] [英] Drag UIButton without it shifting to center [Swift 3]

问题描述

所以我发现了如何使用UIPanGestureRecognizer使按钮可拖动。但我知道如何做的唯一方法是通过中心存储和拖动按钮。这样做的问题是，如果您尝试从角落拖动按钮，按钮会立即从角落移动到中心。我正在寻找的是一种解决方案，可以在移动时将手指放在选定的位置，而不会立即锁定到中心。

So I found out how to make a button draggable using the UIPanGestureRecognizer. But the only way I know how to do it is by storing and dragging the button by the center. The problem with this is if you try and drag the button from a corner, the button instantly shifts from the corner to the center. What I'm looking for is a solution that would keep my finger on a selected place while moving without instantly locking onto the center.

我正在使用的代码：

func buttonDrag(pan: UIPanGestureRecognizer) {
    print("Being Dragged")
    if pan.state == .began {
        print("panIF")
        buttonCenter = button.center // store old button center
    }else {
        print("panELSE")
        let location = pan.location(in: view) // get pan location
        button.center = location // set button to where finger is
    }
}

提前致谢。

推荐答案

这可以通过两种不同的方式完成，一种是使用 GestureRecognizer 你的问题方式，另一种方法是继承 UIView 并实施 touchesBegan ， touchesMoved ， to uchesEnded ， touchesCancelled 一般适用于任何UIView子类可以是 UIButton 或 UILabel 或 UIImageView 等等......

This can be done at least in two different ways, one using GestureRecognizer your question way and other way is subclassing the UIView and implementing the touchesBegan, touchesMoved , touchesEnded, touchesCancelled in general will work for any UIView subclass can be UIButton or UILabel or UIImageView etc...

以你的方式，使用 GestureRecognizer 我做了一些更改，你仍然需要一个var来保持 CGPoint 触摸<$ code> UIButton 所以我们得到相对于UIButton的触摸位置，当拖动继续根据原点触摸位置和运动位置调整UIButton原点

In your way, using GestureRecognizer I make a few changes you still require a var to keep the origin CGPoint of the touch in your UIButton so we get the touch position relative to the UIButton and when the drag continue adjust the UIButton origin according to the origin touch position and the positions of the movement

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var button: UIButton!
    var buttonOrigin : CGPoint = CGPoint(x: 0, y: 0)
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let gesture = UIPanGestureRecognizer(target: self, action: #selector(buttonDrag(pan:)))
        self.button.addGestureRecognizer(gesture)
    }

    func buttonDrag(pan: UIPanGestureRecognizer) {
        print("Being Dragged")
        if pan.state == .began {
            print("panIF")
            buttonOrigin = pan.location(in: button)
        }else {
            print("panELSE")
            let location = pan.location(in: view) // get pan location
            button.frame.origin = CGPoint(x: location.x - buttonOrigin.x, y: location.y - buttonOrigin.y)
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

方法2 UIView在这种情况下的子类UIButton子类

使用此 UIButton 子类

import UIKit

class DraggableButton: UIButton {

    var localTouchPosition : CGPoint?

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesBegan(touches, with: event)
        let touch = touches.first
        self.localTouchPosition = touch?.preciseLocation(in: self)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesMoved(touches, with: event)
    let touch = touches.first
    guard let location = touch?.location(in: self.superview), let localTouchPosition = self.localTouchPosition else{
        return
    }

    self.frame.origin = CGPoint(x: location.x - localTouchPosition.x, y: location.y - localTouchPosition.y)
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesEnded(touches, with: event)
        self.localTouchPosition = nil
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesCancelled(touches, with: event)
        self.localTouchPosition = nil
    }

}

结果

希望这可以帮到你

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