UIRotationGestureRecognizer问题

Question

我正在尝试使用UIRotationGestureRecognizer旋转视图，但问题是旋转的角度不是我视图的中心！这是我的代码：

   UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)];
    [rotationRecognizer setDelegate:self];
    [self.view  addGestureRecognizer:rotationRecognizer];


-(void)rotate:(id)sender {

    if([(UIRotationGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded) {

        _lastRotation = 0.0;
        return;
    }

    CGFloat rotation = 0.0 - (_lastRotation - [(UIRotationGestureRecognizer*)sender rotation]);

    CGAffineTransform currentTransform = textViews.transform;
    CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform,rotation);

    _lastRotation = [(UIRotationGestureRecognizer*)sender rotation];
        [textViews setTransform:newTransform];

}

Answer 1

// create and configure the rotation gesture
    UIRotationGestureRecognizer *rotationGestureRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotationGestureDetected:)];
    [rotationGestureRecognizer setDelegate:self];


    [YOUR_OBJECT_HERE addGestureRecognizer:rotationGestureRecognizer];

// YOUR_OBJECT_HERE - can be any object that you want to rotate (e.g. textView as in your case)


- (void)rotationGestureDetected:(UIRotationGestureRecognizer *)recognizer
{
    UIGestureRecognizerState state = [recognizer state];

    if (state == UIGestureRecognizerStateBegan || state == UIGestureRecognizerStateChanged)
    {
        CGFloat rotation = [recognizer rotation];
        [recognizer.view setTransform:CGAffineTransformRotate(recognizer.view.transform, rotation)];
        [recognizer setRotation:0];
    }
}