ios - 自定义 View Controller 转换偶尔崩溃

Question

我有一个 UIViewController，它使用 iOS 7 中引入的 transitioningDelegate 模式呈现/关闭另一个带有自定义动画的 View Controller 。

我在我的 Crashlytics 日志文件中注意到，这部分代码在生产中偶尔会崩溃，但我一直无法找出原因。它在我的测试中从未崩溃过，看起来只影响了大约 10% 的用户。 iOS 7 和 iOS 8 以及 iPad、iPhone 和 iPod 都会受到影响。

这是来自 Crashlytics 的堆栈跟踪:

Crashed: com.apple.main-thread
EXC_BAD_ACCESS KERN_INVALID_ADDRESS at 0x00014000

Thread : Crashed: com.apple.main-thread
0  libobjc.A.dylib                0x303c3f76 objc_msgSend + 21
1  UIKit                          0x25ed0ac5 -[UIViewController _customAnimatorForDismissedController:] + 64
2  UIKit                          0x25ed0927 -[UIViewController _dismissViewControllerWithTransition:from:completion:] + 538
3  UIKit                          0x25e7e4b3 -[UIViewController dismissViewControllerWithTransition:completion:] + 822
4  UIKit                          0x25e7e4b3 -[UIViewController dismissViewControllerWithTransition:completion:] + 822
5  UIKit                          0x25e7e127 -[UIViewController dismissViewControllerAnimated:completion:] + 222
6  Skin Creator                   0x000f38e7 -[SEUSBodySideChooserViewController imageEditViewController:didFinishWithImage:] (SEUSBodySideChooserViewController.m:251)
7  Skin Creator                   0x000ae2e9 -[SEUSImageEditViewController sendFinishedDelegateMethod] (SEUSImageEditViewController.m:409)
8  Skin Creator                   0x000d585f -[SEUSCloseMenuController circleMenu:didSelectItemAtIndex:] (SEUSCloseMenuController.m:69)
9  Skin Creator                   0x000ceb75 -[SEUSCircleMenu menuButtonPressed:] (SEUSCircleMenu.m:203)
10 UIKit                          0x25dec427 -[UIApplication sendAction:to:from:forEvent:] + 70
11 UIKit                          0x25dec3c9 -[UIControl sendAction:to:forEvent:] + 44
12 UIKit                          0x25dd6fcd -[UIControl _sendActionsForEvents:withEvent:] + 584
13 UIKit                          0x25debdf9 -[UIControl touchesEnded:withEvent:] + 584
14 UIKit                          0x25db0b47 _UIGestureRecognizerUpdate + 10158
15 UIKit                          0x25de5afd -[UIWindow _sendGesturesForEvent:] + 784
16 UIKit                          0x25de53cd -[UIWindow sendEvent:] + 520
17 UIKit                          0x25dbbb5d -[UIApplication sendEvent:] + 196
18 UIKit                          0x2602f4e3 _UIApplicationHandleEventFromQueueEvent + 13874
19 UIKit                          0x25dba59f _UIApplicationHandleEventQueue + 1294
20 CoreFoundation                 0x228dd5e7 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 14
21 CoreFoundation                 0x228dc9fb __CFRunLoopDoSources0 + 222
22 CoreFoundation                 0x228db079 __CFRunLoopRun + 768
23 CoreFoundation                 0x22828981 CFRunLoopRunSpecific + 476
24 CoreFoundation                 0x22828793 CFRunLoopRunInMode + 106
25 GraphicsServices               0x29ba9051 GSEventRunModal + 136
26 UIKit                          0x25e1a981 UIApplicationMain + 1440
27 Skin Creator                   0x000ead6f main (main.m:16)

只是为了让您能更多地理解这一点 [SEUSBodySideChooserViewController imageEditViewController:didFinishWithImage:] 是一个委托(delegate)回调，我在其中关闭了 View Controller 。

我用来呈现 View Controller 的代码

_toPixelEditTransitioningDelegate = [[SEUSFadeInTransitioningDelegate alloc] init];
_imageEditViewController.transitioningDelegate = _toPixelEditTransitioningDelegate;
[self presentViewController:_imageEditViewController animated:YES completion:nil];

我用来关闭 View Controller 的代码

[viewController dismissViewControllerAnimated:YES completion:nil];

我的过渡代表

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    SEUSFadeInTransitioning *transitioning = [[SEUSFadeInTransitioning alloc] init];
    return transitioning;
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    SEUSFadeInTransitioning *transitioning = [[SEUSFadeInTransitioning alloc] init];
    transitioning.reverse = YES;
    return transitioning;
}

实现了 UIViewControllerAnimatedTransitioning 协议(protocol)的 Transition 对象

- (instancetype)init
{
    if (self = [super init])
    {
        _reverse = NO;
        _duration = 0.25f;
    }
    return self;
}

- (void)animateToPixelEdit:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController* overviewVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController* pixelVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    [[transitionContext containerView] addSubview:overviewVC.view];
    [[transitionContext containerView] addSubview:pixelVC.view];

    pixelVC.view.alpha = 0;

    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^
    {
        pixelVC.view.alpha = 1;
    }
    completion:^(BOOL finished)
    {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}

- (void)animateToOverview:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController* pixelVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController* overviewVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    [[transitionContext containerView] addSubview:pixelVC.view];
    [[transitionContext containerView] addSubview:overviewVC.view];

    overviewVC.view.alpha = 0;

    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^
    {
        overviewVC.view.alpha = 1;
    }
    completion:^(BOOL finished)
    {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return _duration;
}

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    if (self.reverse == NO)
    {
        [self animateToPixelEdit:transitionContext];
    }
    else
    {
        [self animateToOverview:transitionContext];
    }
}

有人注意到任何可能出错的地方吗？故障排除真的很困难，因为我无法重现崩溃。

Answer 1

这段代码看起来很漂亮。我怀疑用户能够重复显示或重复关闭您的模式 - 这是这类事情的常见故障点。