按钮旋转45度然后复原

//默认没旋转

open=NO;

if (open==YES) {
            [UIView animateWithDuration:0.03 delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
                btn1.transform = CGAffineTransformIdentity;
            } completion:^(BOOL finished) {
                open=NO;
            }];
        } else {
            [UIView animateWithDuration:0.03 delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
                btn1.transform = CGAffineTransformMakeRotation(45.0f * (M_PI / 180.0f));
            } completion:^(BOOL finished) {
                open=YES;
            }];

}