目标C：开始点和结束点

Question

我正在用手指应用绘制图形。

我想设置一个起点和终点。

我的项目是这样的，它有一个背景可以告诉你画的方向。当用户点击终点时，背景将会改变。

我想这... 上的触摸开始......

drawPoint = [touch locationInView:self.view]; 
    CGRect writingStartPoint = CGRectMake(90, 800, 30, 30); 
    CGRect writingEndPoint = CGRectMake(390, 800, 30, 30); 

    if (CGRectContainsPoint(writingStartPoint, drawPoint)) 
    { 
     //something 
    } 

    if (CGRectContainsPoint(writingEndPoint, drawPoint)) 
     { 
      //change background 
     } 

它不工作。

还有别的办法吗？

Answer 1

你应该检查是在触摸结束矩形触摸移动或结束方法

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    CGPoint drawPoint = [touch locationInView:self.view]; 
    CGRect writingStartPoint = CGRectMake(90, 800, 30, 30); 
    if (CGRectContainsPoint(writingStartPoint, drawPoint)) 
    { 
     //something 
    } 
} 

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    CGPoint drawPoint = [touch locationInView:self.view]; 
    CGRect writingEndPoint = CGRectMake(390, 800, 30, 30); 
    if (CGRectContainsPoint(writingEndPoint, drawPoint)) 
    { 
     //change background if you want user see change without lift finger up 
    } 
} 

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    CGPoint drawPoint = [touch locationInView:self.view]; 
    CGRect writingEndPoint = CGRectMake(390, 800, 30, 30); 
    if (CGRectContainsPoint(writingEndPoint, drawPoint)) 
    { 
     //change background when user lift finger up 
    } 
} 

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { 
    // handle cancel event 
}