关闭视图控制器时发生奇怪的崩溃，自动布局是罪魁祸首?

Strange Crash when dismissing view controller, auto-layout to blame?(关闭视图控制器时发生奇怪的崩溃，自动布局是罪魁祸首?)

问题描述

我遇到了一个非常奇怪的崩溃，这是回溯.

I am experiencing a very strange crash, here is the backtrace.

* thread #1: tid = 0x2403, 0x3379516c CoreFoundation`CFHash + 8, stop reason = EXC_BREAKPOINT (code=EXC_ARM_BREAKPOINT, subcode=0xdefe)
    frame #0: 0x3379516c CoreFoundation`CFHash + 8
    frame #1: 0x33797a9c CoreFoundation`CFBasicHashRemoveValue + 1408
    frame #2: 0x337974ee CoreFoundation`CFDictionaryRemoveValue + 166
    frame #3: 0x3420988e Foundation`-[NSISEngine removeConstraintWithMarker:] + 562
    frame #4: 0x34211dbe Foundation`-[NSLayoutConstraint _removeFromEngine:] + 230
    frame #5: 0x35a954ec UIKit`-[UIView(UIConstraintBasedLayout) _layoutEngine_willRemoveLayoutConstraint:] + 44
    frame #6: 0x358488fc UIKit`__48-[UIScrollView _setAutomaticContentConstraints:]_block_invoke_0 + 148
    frame #7: 0x34208882 Foundation`-[NSISEngine withAutomaticOptimizationDisabled:] + 166
    frame #8: 0x35848838 UIKit`-[UIScrollView _setAutomaticContentConstraints:] + 116
    frame #9: 0x35848e6c UIKit`-[UIScrollView _rememberDependentConstraint:] + 112
    frame #10: 0x35a9e3ae UIKit`___updateViewDependenciesForConstraint_block_invoke_0 + 30
    frame #11: 0x35a954ba UIKit`_updateViewDependenciesForConstraint + 202
    frame #12: 0x35a953da UIKit`-[UIView(UIConstraintBasedLayout) _layoutEngine_didAddLayoutConstraint:roundingAdjustment:mutuallyExclusiveConstraints:] + 154
    frame #13: 0x35a95534 UIKit`-[UIView(UIConstraintBasedLayout) _tryToAddConstraintWithoutUpdatingConstraintsArray:roundingAdjustment:mutuallyExclusiveConstraints:] + 36
    frame #14: 0x3567c2e0 UIKit`-[UIView(Internal) _didMoveFromWindow:toWindow:] + 376
    frame #15: 0x356d34fe UIKit`-[UIScrollView _didMoveFromWindow:toWindow:] + 50
    frame #16: 0x3567c5c6 UIKit`-[UIView(Internal) _didMoveFromWindow:toWindow:] + 1118
    frame #17: 0x35676e52 UIKit`-[UIView(Hierarchy) _postMovedFromSuperview:] + 138
    frame #18: 0x3565e7dc UIKit`-[UIView(Internal) _addSubview:positioned:relativeTo:] + 1300
    frame #19: 0x3565e2c2 UIKit`-[UIView(Hierarchy) addSubview:] + 30
    frame #20: 0x356f68e8 UIKit`-[UITransitionView transition:fromView:toView:removeFromView:] + 972
    frame #21: 0x35937618 UIKit`__91-[UIWindowController transition:fromViewController:toViewController:target:didEndSelector:]_block_invoke_0238 + 388
    frame #22: 0x357499b8 UIKit`-[UIWindowController transition:fromViewController:toViewController:target:didEndSelector:] + 4824
    frame #23: 0x357b9814 UIKit`-[UIViewController _dismissViewControllerWithTransition:from:completion:] + 1708
    frame #24: 0x357057c4 UIKit`-[UIViewController dismissViewControllerWithTransition:completion:] + 912
    frame #25: 0x000ccd40 Capture`-[INFTagSearchViewController cancelButtonTouched:](self=0x1f09ed50, _cmd=0x001b9d5f, sender=0x1e0265c0) + 76 at INFTagSearchViewController.m:48
    frame #26: 0x357470c4 UIKit`-[UIApplication sendAction:to:from:forEvent:] + 72
    frame #27: 0x35747076 UIKit`-[UIApplication sendAction:toTarget:fromSender:forEvent:] + 30
    frame #28: 0x35747054 UIKit`-[UIControl sendAction:to:forEvent:] + 44
    frame #29: 0x3574690a UIKit`-[UIControl(Internal) _sendActionsForEvents:withEvent:] + 502
    frame #30: 0x35746e00 UIKit`-[UIControl touchesEnded:withEvent:] + 488
    frame #31: 0x3566f5f0 UIKit`-[UIWindow _sendTouchesForEvent:] + 524
    frame #32: 0x3565c800 UIKit`-[UIApplication sendEvent:] + 380
    frame #33: 0x3565c11a UIKit`_UIApplicationHandleEvent + 6154
    frame #34: 0x373655a2 GraphicsServices`_PurpleEventCallback + 590
    frame #35: 0x373651d2 GraphicsServices`PurpleEventCallback + 34
    frame #36: 0x33829172 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 34
    frame #37: 0x33829116 CoreFoundation`__CFRunLoopDoSource1 + 138
    frame #38: 0x33827f98 CoreFoundation`__CFRunLoopRun + 1384
    frame #39: 0x3379aebc CoreFoundation`CFRunLoopRunSpecific + 356
    frame #40: 0x3379ad48 CoreFoundation`CFRunLoopRunInMode + 104
    frame #41: 0x373642ea GraphicsServices`GSEventRunModal + 74
    frame #42: 0x356b0300 UIKit`UIApplicationMain + 1120
    frame #43: 0x000a297c Capture`main(argc=1, argv=0x2fd60cfc) + 116 at main.m:16
    frame #44: 0x3bb2bb20 libdyld.dylib`start + 4

你会注意到第 25 帧是我的代码进行的唯一调用，它是 cancelButtonTouched，看起来像.

You will notice frame 25 is the only call my code makes, and it is cancelButtonTouched which looks like.

- (IBAction)cancelButtonTouched:(id)sender {
    [self dismissViewControllerAnimated:YES completion:nil];
}

我不知道发生了什么，我以前从未遇到过这样的问题，根据系统调用，这似乎是一个自动布局问题.我验证了在崩溃发生之前在呈现视图控制器上调用了 viewWillApper，所以我认为它是在呈现视图布局期间发出的.

I am at a loss as to what is going on, I've never had an issue like this before, based on the system calls it appears to be an auto-layout issue. I verified that viewWillApper is called on the presenting view controller before the crash occurs, so I assume it is an issuing during layout of the presenting view.

关于如何将此问题缩小到特定布局约束的任何想法?还是有其他想法?

Any ideas on how to narrow this issue down to a specific layout contstraint? Or any other ideas?

这可以在某些设备上重现，而在其他设备上则很少发生.所以它是间歇性的.

This is reproduceable on some devices, where as on others it rarely if ever happens. So it is intermittent.

更新

断点截图.

更新 2

因此，解除到 presentingViewController 绝对是一个问题，解除两个级别的深度 ([self.presentingViewController.presentingViewControllerdismissViewControllerAnimated:YES completion:nil]) 工作正常，但显然不是想要的结果，我只想回到1级.这进一步让我相信重新布局"视图存在问题.

So it is definitely an issue with dismissing to the presentingViewController, dismissing two levels deep ([self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil]) works fine, but obviously not the desired result, I only want to go back 1 level. This further leads me to believe there is an issue "re-laying" out the view.

推荐答案

基于 Carl Lindberg 的想法，我准备并使用了以下 iOS 类别，现在我没有崩溃了:

Based on idea of Carl Lindberg I prepared and used the following iOS category and I have no crash anymore:

UIView+AddSubviewWithRemovingFromParent.h

UIView+AddSubviewWithRemovingFromParent.h

#import <UIKit/UIKit.h>

@interface UIView (AddSubviewWithRemovingFromParent)

- (void)addSubviewWithRemovingFromParent:(UIView *)view;

@end

UIView+AddSubviewWithRemovingFromParent.m

UIView+AddSubviewWithRemovingFromParent.m

#import "UIView+AddSubviewWithRemovingFromParent.h"

@implementation UIView (AddSubviewWithRemovingFromParent)

- (void)addSubviewWithRemovingFromParent:(UIView *)view {
    if (view.superview != nil) {
        [view removeFromSuperview];
    }
    [self addSubview:view];
}

@end

现在您可以使用 addSubviewWithRemovingFromParent 方法添加 subView 而不是 addSubview 方法，如下所示:

now you can use the addSubviewWithRemovingFromParent method to add the subView instead of addSubview method like this:

UITableViewCell *cell = [[UITableViewCell alloc] init];
[cell.contentView addSubviewWithRemovingFromParent:<viewToAdd>];

总结一下:

1. 在应用所在的控制器中找到所有 addSubView 的引用崩溃了
2. 导入类别 UIView+AddSubviewWithRemovingFromParent.h
3. 使用方法 addSubviewWithRemovingFromParent 而不是 addSubView

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