Question

我想在拖动时从用户的手指获取坐标。我试过这段代码，但是它说坐标总是{0,0}，怎么了？

- (IBAction)Drag{
UIPanGestureRecognizer *Recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(dragged)];
[self.view addGestureRecognizer:Recognizer];
}
-(void) dragged{
UITouch *touch ;
CGPoint location = [touch locationInView:touch.view];
NSLog(@"%@", NSStringFromCGPoint (location));
}

我也试过了NSLog(@"%.2f %.2f" location.x, location.y);并得到了同样的结果。感谢

Answer 1

这是很正常的，你使用的是touch而没有给它赋值。

手势识别器的动作采用一个参数，即识别器本身，而后者又有一个locationInView:方法，所以你应该使用它。此外，您需要检查识别器的状态。最后，您可能不希望在需要时添加手势识别器，只需从头开始添加。

// probably in your viewDidLoad
UIPanGestureRecognizer *Recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self
                                       action:@selector(panGestureRecognizerAction:)];
[self.view addGestureRecognizer:Recognizer];

- (void)panGestureRecognizerAction:(UIPanGestureRecognizer *)recognizer
{
    if (recognizer.state == UIGestureRecognizerStateBegan ||
        recognizer.state == UIGestureRecognizerStateChanged)
    {
        CGPoint location = [recognizer.state locationInView:touch.view];
        NSLog(@"%@", NSStringFromCGPoint (location));
    }
}

使用CGPoint拖动坐标

1 个答案: