旋转动画

//旋转动画
    CABasicAnimation* rotationAnimation =
    [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];//"z"还可以是“x”“y”，表示沿z轴旋转
    rotationAnimation.toValue = [NSNumber numberWithFloat:(2 * M_PI) * 2];
    rotationAnimation.duration = 1.5f;
    rotationAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; //缓入缓出
    [self.myTabBar.plusView.layer addAnimation:rotationAnimation forKey:nil];