iOS 9自定义转换 - 未调用animationControllerForDismissedController

Question

我是iOS开发中的新手，最近在iOS 9中通过自定义过渡遇到了这个问题。

我有一个对象符合UIViewControllerTransitioningDelegate协议并实现animationControllerForDismissedController ，如：

@implementation MyCustomizedTransitioningDelegate

#pragma mark - UIViewControllerTransitioningDelegate

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    MyCustomizedTransitionAnimator *animator = [[MyCustomizedTransitionAnimator alloc] init];
    animator.presenting = NO;
    return animator;
}

@end

触发模态转换的过程如下：

@implementation MyViewController

#pragma mark - Initializers

+ (MyCustomizedTransitioningDelegate *)modalTransitioningDelegateSingletonInstance;
{
    static MyCustomizedTransitioningDelegate *delegateInst = nil;
    static dispatch_once_t onceToken = 0;
    dispatch_once(&onceToken, ^{
        delegateInst = [[MyCustomizedTransitioningDelegate alloc] init];
    });

    return delegateInst;
}

#pragma mark - UIViewController

- (void)dismissViewControllerAnimated:(BOOL)animated completion:(void (^)(void))completion;
{
    [self prepareForDismissViewControllerAnimated:animated completion:&completion];
    [super dismissViewControllerAnimated:animated completion:completion];
}

- (void)prepareForDismissViewControllerAnimated:(BOOL)animated completion:(dispatch_block_t *)completion;
{
    self.presentedViewController.modalPresentationStyle = UIModalPresentationCustom;
    self.presentedViewController.transitioningDelegate = [[self class] modalTransitioningDelegateSingletonInstance];      
}

@end

由于未调用animationControllerForDismissedController方法，因此未创建MyCustomizedTransitionAnimator ，这导致其animateTransition未被调用，这会导致我的应用程序出现意外问题。 （抱歉我的英语不好......）

我还附上了iOS8和iOS9的堆栈跟踪截图。 在iOS 8中，在下面的堆栈跟踪之后调用animationControllerForDismissedController 。

但是在iOS9中，提前以某种方式调用transitionDidFinish ，我猜可能会阻止animationControllerForDismissedController被调用？

我想知道这是不是iOS 9的错误。 任何解释或解决方案将不胜感激！

Answer 1

我遇到了同样的问题。

我希望这会对某人有所帮助。

为我修复的是将使用UIViewControllerTransitioningDelegate协议的对象作为变量实例来保持与它的强关系。

我认为因为它在第一次呈现视图后被解雇了。

Answer 2

我遇到过同样的问题。

原来我需要在包含触发按钮的UIViewController的navigationController上设置委托。

有这个旧代码不起作用：

UIViewController *dvc = [self sourceViewController];
TransitionDelegate *transitionDelegate = [TransitionDelegate new];

dvc.modalPresentationStyle = UIModalPresentationCustom;
dvc.transitioningDelegate = transitionDelegate;

[dvc dismissViewControllerAnimated:YES completion:nil];

我将第一行更改为：

UIViewController *dvc = [self sourceViewController].navigationController;

它起作用了。

希望这可以帮助。

Answer 3

你需要说：

MyDestinationViewController *viewController = [[MyDestinationViewController alloc] init];
MyCustomizedTransitioningDelegate *transitioningDelegate = [[MyCustomizedTransitioningDelegate alloc]init];
viewController.transitioningDelegate = transitioningDelegate;
viewController.modalPresentationStyle = UIModalPresentationCustom;
[self presentViewController: viewController animated:YES completion:nil];

或者，如果你正在使用segues，那么在prepareForSegue中会说：

MyDestinationViewController *toVC = segue.destinationViewController;
MyCustomizedTransitioningDelegate *transitioningDelegate = [[MyCustomizedTransitioningDelegate alloc]init];
toVC.transitioningDelegate = transitioningDelegate;