触摸开始，触摸结束，触摸移动用于移动UIView

Question

我需要拖动我的UIView对象。我使用这个代码，但它不工作

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;
        }
    }

}

Answer 1

我建议使用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，使用手势识别器要比使用touchesBegan、touchesEnded、touchesMoved简单得多。我将在UIPanGestureRecognizer不起作用的情况下使用这些。

Answer 2

这是用于移动UIView对象的工作代码

浮动oldX、oldY；BOOL拖动；

- (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;
        }
    }
}

Answer 3

您的代码中有一些奇怪的东西。

您询问self中的位置，一些UIView可能包含您要检查的UILabel。这就引出了一个问题，即为什么不将touchesXXX添加到您的某个UILabel子类中。

当您使用根据其superview.bounds（您询问触摸位置的父级UIView）定义的label.frame时，这会被取消，但这并不能成为了解情况的最直接方法。

Answer 4

有了这段代码，我可以将UIView对象移动到任何地方。我的ViewController.swift是这样的。

// 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

希望它能有所帮助，尽管这是另一种方法，而不是上面提到的方法。