Question

我正在尝试创建一个控件，用户可以触摸并移动框架内的按钮。这是我的代码。

- (void)wasDragged:(UIButton *)button withEvent:(UIEvent *)event
{

   UITouch *touch = [[event touchesForView:button] anyObject];

    // get delta
    CGPoint previousLocation = [touch previousLocationInView:button];
    CGPoint location = [touch locationInView:button];
    CGFloat delta_x = location.x - previousLocation.x;
    CGFloat delta_y = location.y - previousLocation.y;

    // move button
    button.center = CGPointMake(button.center.x + delta_x,
                                button.center.y + delta_y);   


}

我可以移动按钮（通过触摸和拖动），但是如何限制按钮，以便它只能在矩形框内向左/向右移动。

Answer 1

也许这种方法会对你有所帮助。我在一段时间前做过的简单的乒乓球比赛中使用过它。这是一个UIView，是乒乓球比赛的反弹垫。我限制了反射垫在x方向上的移动，而不是在屏幕边界之外。

如果不清楚，请写评论，我会尝试解释。

// Method for movement of the bouncing pad. Restricted movement to x-axis inside of bounds.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

    UITouch *aTouch = [touches anyObject];
    CGPoint loc = [aTouch locationInView:self];
    CGPoint prevloc = [aTouch previousLocationInView:self];

    CGRect myFrame = self.frame;

    // Checking how far we have moved from the previous location
    float deltaX = loc.x - prevloc.x;

    // Note that we only update the x-position of the pad to prevent it from moving in the y-direction.
    myFrame.origin.x += deltaX;

    // Making sure that the bouncePad cannot move outside of the screen
    if(myFrame.origin.x < 0){
        myFrame.origin.x = 0;
    } else if (myFrame.origin.x + myFrame.size.width > [UIScreen main Screen].bounds.size.width) {
        myFrame.origin.x = [UIScreen mainScreen].bounds.size.width - myFrame.size.width;
    }

    // Setting the bouncing pad frame to the one with the updated position from the touches moved event.
    [self setFrame:myFrame];

}

Answer 2

如果您想左右移动，只应更改 X 而不是Y，只需更改下面的代码

// move button YOUR CODE
button.center = CGPointMake(button.center.x + delta_x,
                            button.center.y + delta_y);

// move button REMOVED + delta_y
button.center = CGPointMake(button.center.x + delta_x,
                            button.center.y);

Answer 3

要么对极值的坐标进行硬编码，要么在视图（矩形）内进行硬编码，并使用剪辑来界定按钮

在像开关一样的矩形框内移动一个按钮（左/右）

3 个答案: