addSubview动画仅在第二次后才能工作

Question

I am trying to make my label appear with animation:

- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
    if (isShowingRectangleLabel == NO) {
    [UIView transitionWithView:rectangleLabel duration:0.5
                       options:UIViewAnimationOptionTransitionCrossDissolve
                    animations:^ { [self.view addSubview:rectangleLabel]; }
                    completion:nil];
        NSLog(@"action");
        isShowingRectangleLabel = YES;
    } else {
        [UIView transitionWithView:rectangleLabel duration:0.5
                       options:UIViewAnimationOptionTransitionFlipFromBottom
                    animations:^ { [rectangleLabel removeFromSuperview]; }
                    completion:nil];
        isShowingRectangleLabel = NO;
    }

}

But this animation works only after second adding to subview. How can I fix it?

EDIT To clarify, addSubview works but without animation.

Answer 1

Do this:

- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
    if (isShowingRectangleLabel == NO) {
    [UIView transitionWithView:self.view duration:0.5
                       options:UIViewAnimationOptionTransitionCrossDissolve
                    animations:^ { [self.view addSubview:rectangleLabel]; }
                    completion:nil];
        NSLog(@"action");
        isShowingRectangleLabel = YES;
    } else {
        [UIView transitionWithView:self.view duration:0.5
                       options:UIViewAnimationOptionTransitionFlipFromBottom
                    animations:^ { [rectangleLabel removeFromSuperview]; }
                    completion:nil];
        isShowingRectangleLabel = NO;
    }

}