目标C：起点和终点

Question

我正在用手指应用程序制作绘图。

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，告诉你绘制的方向。当用户点击结束点时，背景将会改变。

我试过这个...... 接触开始......

    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
        }

它不起作用。

还有其他办法吗？

Answer 1

你应该检查触摸移动或结束方法中的结束矩形触摸

- (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
}