- (void)startAnimation {
    CABasicAnimation* rotationAnimation;
    rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2.0 ];
    rotationAnimation.duration = 1;
    rotationAnimation.cumulative = YES;
    rotationAnimation.repeatCount = 3;
    [_loadingImage.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
}