我有一个程序,其中CALayer必须旋转到某个值.
如何确定CALayer的当前旋转？
我有一个UIRotationGestureRecognizer来旋转图层：
如何确定CALayer的当前旋转？
我有一个UIRotationGestureRecognizer来旋转图层：
- (void)handleGesture:(UIGestureRecognizer *)gestureRecognizer
{
if (gestureRecognizer == rotationGestureRecognizer) {
NSLog(@"gestureRecRotation: %f",rotationGestureRecognizer.rotation);
CATransform3D current = _baseLayer.transform;
_baseLayer.transform = CATransform3DRotate(current,rotationGestureRecognizer.rotation * M_PI / 180,1.0);
}
}
我从一层必须旋转一定数量的拼图开始.那么如何获得当前图层的旋转？
解决方法
你可以做数学,得到这样的角度：
CATransform3D transform = _baseLayer.transform; CGFloat angle = atan2(transform.m12,transform.m11);
但是更容易做到如下：
CGFloat angle = [(NSNumber *)[_baseLayer valueForKeyPath:@"transform.rotation.z"] floatValue];
Core Animation extends the key-value coding protocol to allow getting and setting of the common values of a layer’s CATransform3D matrix through key paths. Table 4 describes the key paths for which a layer’s transform and sublayerTransform properties are key-value coding and observing compliant
