相对于触摸移动 UIView答案

【问题标题】：Move UIView with relation to touch相对于触摸移动 UIView
【发布时间】：2011-05-28 04:36:45
【问题描述】：

我正在尝试根据用户的触摸移动 UIView。

这是我目前拥有的：

int oldX, oldY;
BOOL dragging;

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

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

    if (CGRectContainsPoint(window.frame, touchLocation)) {
        dragging = YES;
        oldX = touchLocation.x;
        oldY = touchLocation.y;
    }

}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:self.view];

    if (CGRectContainsPoint(window.frame, touchLocation) && dragging) {
        CGRect frame;
        frame.origin.x = (window.frame.origin.x + touchLocation.x - oldX);
        frame.origin.y = (window.frame.origin.y + touchLocation.y - oldY);
        window.frame = frame;

    }

}

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

视图不断从一个位置闪烁到另一个位置，我不知道还能做什么。

任何帮助表示赞赏。

【问题讨论】：

标签： iphone objective-c ios uiview

【解决方案1】：

您想要的是使用 iOS 3.2 中引入的UIPanGestureRecognizer。您可以像这样简单地使用它（来自您的 UIViewController 子类）：

-(void)viewDidLoad;
{
   [super viewDidLoad];
   UIPanGestureRecognizer* pgr = [[UIPanGestureRecognizer alloc] 
                                       initWithTarget:self
                                               action:@selector(handlePan:)];
   [self.panningView addGestureRecognizer:pgr];
   [pgr release];
}

-(void)handlePan:(UIPanGestureRecognizer*)pgr;
{
   if (pgr.state == UIGestureRecognizerStateChanged) {
      CGPoint center = pgr.view.center;
      CGPoint translation = [pgr translationInView:pgr.view];
      center = CGPointMake(center.x + translation.x, 
                           center.y + translation.y);
      pgr.view.center = center;
      [pgr setTranslation:CGPointZero inView:pgr.view];
   }
}

【讨论】：

如果你的view是一个UIImageview，确保userInteractionEnabled 为YES 像：_imageView.userInteractionEnabled = YES;

【解决方案2】：

修改 touchesBegan 和 touchesMoved 方法，如下所示。

float oldX, oldY;
BOOL dragging;

touchesBegan:withEvent: 方法。

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

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

    if (CGRectContainsPoint(window.frame, touchLocation)) {

        dragging = YES;
        oldX = touchLocation.x;
        oldY = touchLocation.y;
    }
}

touchesMoved:withEvent: 方法。

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

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

    if (dragging) {

        CGRect frame = window.frame;
        frame.origin.x = window.frame.origin.x + touchLocation.x - oldX;
        frame.origin.y =  window.frame.origin.y + touchLocation.y - oldY;
        window.frame = frame;
    }
}

touchesEnded:withEvent: 方法。

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

    dragging = NO;
}

【讨论】：

window是你拖动的对象吗？
是的，它是在 Interface Builder 中创建的视图。
它好多了，但奇怪的是，一碰到它就会缩小到一边。
我将 oldX 和 oldY 更改为浮动，一切正常...感谢您的帮助！

【解决方案3】：

这里是 Swift 中的代码，这是一个稍微通用的版本，可以与在屏幕上创建的 ImageView 一起使用。

let panGestureRecongnizer = UIPanGestureRecognizer(target:self, action: "handlepan:")
imageView.addGestureRecognizer(panGestureRecongnizer)

func handlepan(sender: UIPanGestureRecognizer) {
    if (sender.state == UIGestureRecognizerState.Changed) {
        var center = sender.view?.center
        let translation = sender.translationInView(sender.view)
        center = CGPointMake(center!.x + translation.x, center!.y + translation.y)
        sender.view?.center = center!
        sender .setTranslation(CGPointZero, inView: sender.view)
    }
}

【讨论】：

【解决方案4】：

//以上 Swift 4.0 中的答案

var 拖动：Bool = false

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

    let touch = event?.allTouches?.first
    let touchPoint = touch?.location(in: self.window)

    i
    if viewToDrag.frame.contains(touchPoint!){
        dragging = true
    }

}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    let touch = event?.allTouches?.first
    let touchPoint = touch?.location(in: self.window)

    if (dragging) {

        viewToDrag.center = CGPoint(x: (touchPoint?.x)!, y: (touchPoint?.y)!)

    }

}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    dragging = false
}

【讨论】：

你能解释一下你做了什么或改变了什么或突出错误吗？
请解释您的代码行，以便其他用户了解其功能

【解决方案5】：

@PeyLoW 答案是我建议的答案，并对父边界添加限制

-(void)handlePan:(UIPanGestureRecognizer*)pgr;
{
    if (pgr.state == UIGestureRecognizerStateChanged) {
        CGPoint center = pgr.view.center;
        CGPoint translation = [pgr translationInView:pgr.view];
        center = CGPointMake(center.x + translation.x,
                             center.y + translation.y);

        if ([self pointInside:center withEvent:nil])
        {
            pgr.view.center = center;
            [pgr setTranslation:CGPointZero inView:pgr.view];
        }
    }
}

【讨论】：