具有尾随约束的约束不稳定问题的 Objective-c 动画

Question

我正在使用objective-c开发一个IOS应用程序。在对视图的约束进行动画处理时，我遇到了一个不稳定问题。动画在帧的最终位置方面效果很好，但随机地，第一个动画块的尾随(右(约束被省略(左约束永远不会达到 -20 常量值(，但是前导(左(、顶部和底部约束按预期工作。

请看我上传的视频。在第一次点击中，动画按预期工作，但在第二次点击中出现问题。请指教。

显示问题的视频

- (void)animateTransition:(nonnull id<UIViewControllerContextTransitioning>)transitionContext {
// 1
UIView *containerView = transitionContext.containerView;
UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
// 2
[containerView addSubview:toViewController.view];
if([toViewController isKindOfClass:[ImageViewController class]]){
ImageViewController *vcImage = (ImageViewController*)toViewController;
vcImage.constraintLeft.constant = 20;
vcImage.constraintTop.constant = self.selectedCardFrame.origin.y + 60.0;
vcImage.constraintRight.constant = 20.0;
vcImage.constraintBottom.constant = 0;//self.CollectionView.bounds.size.height - (self.selectedCardFrame.origin.y + self.selectedCardFrame.size.height);
[toViewController.view layoutIfNeeded];
NSTimeInterval duration = [self transitionDuration:transitionContext];
[toViewController.view layoutIfNeeded];
[UIView animateWithDuration:duration animations:^{
//First animation block
vcImage.constraintRight.constant = -20.0;
vcImage.constraintLeft.constant = -20.0;
vcImage.constraintTop.constant = -20.0;
vcImage.constraintBottom.constant = 0;
[toViewController.view layoutIfNeeded];
//toViewController.configureRoundedCorners(shouldRound: false)
} completion:^(BOOL finished) {
//Second animation block
[UIView animateWithDuration:duration animations:^{
vcImage.constraintLeft.constant = 0;
vcImage.constraintTop.constant = 0.0;
vcImage.constraintRight.constant = 0;
vcImage.constraintBottom.constant = 0;
[toViewController.view layoutIfNeeded];
//toViewController.configureRoundedCorners(shouldRound: false)
} completion:^(BOOL finished) {
[transitionContext completeTransition:finished];
}];
}];
}

}

在@Sh_Khan的注释之后更新了代码。

- (void)animateTransition:(nonnull id<UIViewControllerContextTransitioning>)transitionContext {
// 1
UIView *containerView = transitionContext.containerView;
UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
// 2
[containerView addSubview:toViewController.view];
if([toViewController isKindOfClass:[ImageViewController class]]){
ImageViewController *vcImage = (ImageViewController*)toViewController;
NSTimeInterval duration = [self transitionDuration:transitionContext];
[UIView animateWithDuration:0 animations:^{
vcImage.constraintLeft.constant = 20;
vcImage.constraintTop.constant = self.selectedCardFrame.origin.y + 60.0;
vcImage.constraintRight.constant = 20.0;
vcImage.constraintBottom.constant = 0;
[toViewController.view layoutIfNeeded];
} completion:^(BOOL finished) {
[UIView animateWithDuration:duration animations:^{
//First animation block
vcImage.constraintRight.constant = -20.0;
vcImage.constraintLeft.constant = -20.0;
vcImage.constraintTop.constant = -20.0;
vcImage.constraintBottom.constant = 0;
[toViewController.view layoutIfNeeded];
//toViewController.configureRoundedCorners(shouldRound: false)
} completion:^(BOOL finished) {
//Second animation block
[UIView animateWithDuration:duration animations:^{
vcImage.constraintLeft.constant = 0;
vcImage.constraintTop.constant = 0.0;
vcImage.constraintRight.constant = 0;
vcImage.constraintBottom.constant = 0;
[toViewController.view layoutIfNeeded];
//toViewController.configureRoundedCorners(shouldRound: false)
} completion:^(BOOL finished) {
[transitionContext completeTransition:finished];
}];
}];
}];
}

}

Answer 1

在设置图像视图之前，请尝试重新定向照片。 有人告诉我，图像视图很难确定图像的方向。 我曾经在过渡期间发生过这种情况，并会解释为什么您只在某些时候看到这种行为。我对 Objective C 有点生疏，但在设置 imageView 图像之前试一试并使用它。

-(UIImage*)normalizeImage:(UIImage*)currentImage {
if (currentImage.imageOrientation == UIImageOrientationUp){
return currentImage;
}
UIGraphicsBeginImageContextWithOptions(currentImage.size, NO, currentImage.scale);
[currentImage drawInRect:CGRectMake(0, 0, currentImage.size.width, currentImage.size.height)];
UIImage *_newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return _newImage;
}