Question

我正在为iPad制作一个图形计算器应用程序，我想添加一个功能，用户可以在图表视图中点击一个区域，弹出一个文本框，显示他们触摸的点的坐标。我如何从中获得CGPoint？

Answer 1

你有两种方式......

1

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

在这里，您可以从当前视图中获取位置...

2

UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapped:)];
[tapRecognizer setNumberOfTapsRequired:1];
[tapRecognizer setDelegate:self];
[self.view addGestureRecognizer:tapRecognizer];

这里，当您想要使用主视图或主视图的子视图做某事时，此代码使用

Answer 2

试试这个

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
  UITouch *touch = [touches anyObject];

  // Get the specific point that was touched
  CGPoint point = [touch locationInView:self.view]; 
  NSLog(@"X location: %f", point.x);
  NSLog(@"Y Location: %f",point.y);

}

如果您更愿意看到用户将手指从屏幕上抬起而不是放在他们的位置，您可以使用“touchesEnded”。

Answer 3

将UIGestureRecognizer与地图视图一起使用可能更好更简单，而不是尝试将其子类化并手动拦截触摸。

步骤1：首先，将手势识别器添加到地图视图中：

 UITapGestureRecognizer *tgr = [[UITapGestureRecognizer alloc] 
    initWithTarget:self action:@selector(tapGestureHandler:)];
 tgr.delegate = self;  //also add <UIGestureRecognizerDelegate> to @interface
 [mapView addGestureRecognizer:tgr];

步骤2：接下来，实现shouldRecognizeSimultaneouslyWithGestureRecognizer并返回YES，这样您的点击手势识别器可以与地图同时工作（否则地图上的点击不会被地图自动处理）：

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer 
shouldRecognizeSimultaneouslyWithGestureRecognizer
    :(UIGestureRecognizer *)otherGestureRecognizer
{
   return YES;
}

步骤3：最后，实现手势处理程序：

- (void)tapGestureHandler:(UITapGestureRecognizer *)tgr
{
   CGPoint touchPoint = [tgr locationInView:mapView];

   CLLocationCoordinate2D touchMapCoordinate 
    = [mapView convertPoint:touchPoint toCoordinateFromView:mapView];

   NSLog(@"tapGestureHandler: touchMapCoordinate = %f,%f", 
    touchMapCoordinate.latitude, touchMapCoordinate.longitude);
}

Answer 4

只想投入一个 Swift 4 答案，因为API看起来完全不同。

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touch = event?.allTouches?.first {
        let loc:CGPoint = touch.location(in: touch.view)
        //insert your touch based code here
    }
}

OR

let tapGR = UITapGestureRecognizer(target: self, action: #selector(tapped))
view.addGestureRecognizer(tapGR)

@objc func tapped(gr:UITapGestureRecognizer) {
    let loc:CGPoint = gr.location(in: gr.view)  
    //insert your touch based code here
}

在这两种情况下，loc都将包含视图中触及的点。

Answer 5

如果您使用UIGestureRecognizer或UITouch对象，则可以使用locationInView:方法检索用户触摸的给定视图中的CGPoint。

Answer 6

func handleFrontTap(gestureRecognizer: UITapGestureRecognizer) {
    print("tap working")
    if gestureRecognizer.state == UIGestureRecognizerState.Recognized { 
        `print(gestureRecognizer.locationInView(gestureRecognizer.view))`
    }
}

如何从tapped位置获取CGPoint？

6 个答案: