iphone - UIImageview 上的 UIRotationGestureRecognizer

Question

如何在 iOS SDK 中用两个手指触摸旋转 UIImageView..我知道这很简单但是因为我是这项技术的新手所以无法理解...

如何使用 UIRotationGestureRecognizer 来实现这个...

请帮我解决这个问题...

谢谢。

Answer 1

在 View 加载或 ImageView 创建函数上编写此代码:m_ctrlImgVwShowImage - 你的 ImageView

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

//lastRotation is a cgfloat member variable

-(void)rotate:(id)sender {
    if([(UIRotationGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded) {
        _lastRotation = 0.0;
        return;
    }

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

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

    [m_ctrlImgVwShowImage setTransform:newTransform];

    _lastRotation = [(UIRotationGestureRecognizer*)sender rotation];
}