touchesBegan、touchesEnded和touchesMoved用于移动UIView。

Question

touchesBegan、touchesEnded和touchesMoved用于移动UIView。

20

我需要拖动我的UIView对象。我使用了这段代码，但它不起作用。

float oldX, oldY;
BOOL dragging;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:self];

    if ([[touch.view class] isSubclassOfClass:[UILabel class]]) {
        UILabel *label = (UILabel *)touch.view;
        if (CGRectContainsPoint(label.frame, touchLocation)) {
            dragging = YES;
            oldX = touchLocation.x;
            oldY = touchLocation.y;
        }
    }


}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

    dragging = NO;
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:self];

    if ([[touch.view class] isSubclassOfClass:[UILabel class]]) {
        UILabel *label = (UILabel *)touch.view;

        if (dragging) {
            CGRect frame = label.frame;
            frame.origin.x = label.frame.origin.x + touchLocation.x - oldX;
            frame.origin.y =  label.frame.origin.y + touchLocation.y - oldY;
            label.frame = frame;
        }

    }


}

- Matrosov Oleksandr

请查看此stackoverflow答案：https://dev59.com/uW445IYBdhLWcg3wNXg_#4983124 - luksfarris

实际上发生了什么？ - trojanfoe

问题与移动对象有关。当我点击对象时，它必须记住坐标，然后在方法-touchesMoved中重新计算其框架时应该移动，但它没有移动。它只朝一个方向移动。 - Matrosov Oleksandr

4个回答

14

这是移动UIView对象的工作代码

float oldX, oldY; BOOL dragging;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:touch.view];
    if ([[touch.view class] isSubclassOfClass:[UILabel class]]) {
        dragging = YES;
        oldX = touchLocation.x;
        oldY = touchLocation.y;
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    dragging = NO;
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:touch.view];    
    if ([[touch.view class] isSubclassOfClass:[UILabel class]]) {
        UILabel *label = (UILabel *)touch.view;
        if (dragging) {
            CGRect frame = label.frame;
            frame.origin.x = label.frame.origin.x + touchLocation.x - oldX;
            frame.origin.y = label.frame.origin.y + touchLocation.y - oldY;
            label.frame = frame;
        }
    }
}

- Matrosov Oleksandr

0

你的代码有些奇怪。

你在 self 中寻找位置，它是一个 UIView，里面很可能包含了你想要检查的 UILabel。这引出了一个问题，为什么你不把 touchesXXX 添加到你自己的 UILabel 子类中呢？

虽然这可以取消掉，因为你正在使用 label.frame 来定义其 superview.bounds（即你要求触摸位置的父 UIView），但这并不是最直接的方式来理解正在发生的事情。

- verec

是的，你说得对。我已经将self更改为touch.view，并删除了用于检查点是否在矩形内的if块。谢谢。 - Matrosov Oleksandr

0

使用这段代码，我可以将我的UIView对象移动到任何位置。我的ViewController.swift文件如下。

// code from below

import UIKit

class ViewController: UIViewController {

    var location = CGPoint(x: 0, y: 0)

    @IBOutlet weak var Person: UIImageView!

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

        var touch : UITouch! =  touches.first! as UITouch

        location = touch.location(in: self.view)

        Person.center = location

    }

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

        var touch : UITouch! =  touches.first! as UITouch

        location = touch.location(in: self.view)

        Person.center = location
    }

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

        Person.center = CGPoint(x: 160, y: 330)
    }

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


}

//ends

希望这能有所帮助，虽然这是一种与问题中提到的方法不同的方式。

- Nappa

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可以查看英文原文，
原文链接

- Jaybit · Accepted Answer

我建议使用一个 UIPanGestureRecognizer：

-(void)dragging:(UIPanGestureRecognizer *)gesture
{
    // Check if this is the first touch
    if(gesture.state == UIGestureRecognizerStateBegan)
    {
        // Store the initial touch so when we change positions we do not snap
        self.panCoord = [gesture locationInView:gesture.view];
        [self.view bringSubviewToFront:gesture.view];

    }

    CGPoint newCoord = [gesture locationInView:gesture.view];

    // Create the frame offsets to use our finger position in the view.
    float dX = newCoord.x-self.panCoord.x;
    float dY = newCoord.y-self.panCoord.y;

    gesture.view.frame = CGRectMake(gesture.view.frame.origin.x+dX,
                                    gesture.view.frame.origin.y+dY,
                                    gesture.view.frame.size.width, 
                                    gesture.view.frame.size.height);
}

这只是我的偏好。对我来说，使用手势识别器比使用 touchesBegan、touchesEnded和 touchesMoved 要简单得多。在无法使用 UIPanGestureRecognizer 的情况下，我会使用这些。