view无限旋转

- (void) showRefreshAnimation {
    [UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
        self.refreshIcon.transform = CGAffineTransformRotate(self.refreshIcon.transform, 360);
    } completion:^(BOOL finished) {
        if (self.canRotate) {
            [self showRefreshAnimation];
        }
        else {
//            self.refreshIcon.transform = CGAffineTransformRotate(CGAffineTransformIdentity, 0);
        }
    }];
}