iphone - addSubview 动画仅在第二次后有效

Question

我试图让我的标 checkout 现动画:

- (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;
    }

}

但是这个动画只有在第二次添加到 subview 后才能工作。我该如何解决？

编辑 为了澄清， addSubview作品，但没有动画。

Answer 1

做这个:

- (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;
    }

}