使用 CATransform3DMakeRotation 左右旋转 UIView

Question

在我的应用程序中，我使用 CATransform3DMakeRotation 来旋转 UIView，在其上移动手指，尝试想象一个旋钮。 我的问题是，一切都运转良好，移动如我所愿，但当我触摸它并开始旋转时，它会在中心旋转 180 度，我不明白为什么。

我向您展示我的代码：

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
        {
        if (Tag ==subView.tag)

            {
                   CGPoint Location  = [[touches anyObject] locationInView:subView.superview];
                 int x = subView.center.x;
                 int y = subView.center.y;
                 float dx = Location.x - x;
                 float dy = Location.y - y;
                 double a = atan2f(-dx, dy);

                subView.layer.position  = subView.center;
                 subView.layer.transform = CATransform3DMakeRotation(a, 0, 0, 1);
        }}




-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{

if (Tag ==subView.tag) 

    {   
        [self touchesBegan:touches withEvent:event];
}}

编辑：这里我如何解决问题

CGPoint Location  = [withTheTouch locationInView:theViewToRotate.superview];
    NSLog(@"location x%f",Location.x);
    NSLog(@"location y%f",Location.y);
    int x = theViewToRotate.center.x;
    int y = theViewToRotate.center.y;
    NSLog(@" X %i",x);
    NSLog(@" Y %i",y);
    float dy;
    float dx;

    if (Location.y < theViewToRotate.center.y) 
    {
        dx = x- Location.x;
        dy = y- Location.y;

        NSLog(@"dx %f",dx);
        NSLog(@"dy %f",dy);
        NSLog(@"sopra il View.Center");

    } else {

        dx = Location.x - x;
        dy = Location.y - y;
        NSLog(@"sotto il View.Center");

    }
    float ang = atan2(-dx, dy);
    NSLog(@"anchorPoint %@",NSStringFromCGPoint(theViewToRotate.layer.anchorPoint));
    NSLog(@"Position %@",NSStringFromCGPoint(theViewToRotate.layer.position));
    NSLog(@"angle %f",ang);
    //theViewToRotate.layer.position  = theViewToRotate.center;


if(ang)

     {
        theViewToRotate.layer.transform = CATransform3DMakeRotation(ang, 0, 0, 1);  //ruoto sul vettore Z

    } 
    else 
    {
        //theViewToRotate.frame = CGRectMake(theViewToRotate.frame.origin.x, theViewToRotate.frame.origin.y , theViewToRotate.frame.size.width, theViewToRotate.frame.size.height );
    }

问题出在我在视图中触摸的点上。

现在我需要了解如何锁定两个角度之间的旋转。我不需要 360° 旋转。

Answer 1

您好，发生这种情况的原因是视图本身已有旋转。您需要获取当前的旋转并从那里开始旋转。

你所做的总是从这里开始 CATransform3DMakeRotation(a, 0, 0, 1);

它有自己预先定义的旋转。因此当你触摸它时会发生 180 度的转变。如果您从当前视图的旋转开始旋转，则不会发生这种情况。

希望有帮助