我目前正在开发一个iOS应用程序崩溃并生成下面提供的崩溃报告。我们认为应用程序因快速枚举时发生突变而崩溃，但错误发生在NSISEngine中。
我们还认为该问题与表视图的约束有关。此表视图显示从Rest Services获取的信息，我们以编程方式更新viewWillAppear（）中的DataSource。
我们以编程方式添加的一些约束如下：
Method:
1.cellForRowAtIndexPath（）
约束：
a. Updated UILabel with attributed String to set line height:
[attributedString addAttribute:NSFontAttributeName value:self.font range:NSMakeRange(0, text.length)];
self.attributedText = attributedString;
b. Updated UIImage:
myCell.myLogo.layer.masksToBounds =YES;
myCell.myLogo.layer.opaque = NO;
[[myCell.myLogo layer] setCornerRadius:4.];
c. Border for Table View cell
mySecondCell.secondCellContainerView.layer.masksToBounds = YES;
[mySecondCell.secondCellContainerView.layer setCornerRadius:3.7];
[mySecondCell.secondCellContainerView addBorderWithColorRed:@214 Green:@214 Blue:@214];
[myCell.myLogo addBorderWithColorRed:@214 Green:@214 Blue:@214];
约束： 我们根据动态内容计算高度。
我们正在使用StoryBoard，并且使用自动布局设置了一些约束。
我搜索了很多但无法找到类似于我的应用生成的崩溃报告。我是iOS编程的新手。有人可以帮我调试这个崩溃报告吗？如果存在导致此问题的约束，有人可以帮我弄清楚吗？提前谢谢。
Incident Identifier: F155875B-9FD3-425F-85B9-7595617AF52A
CrashReporter Key: aaa79870161ff1e371394b881a26e97f0066f464
Hardware Model: iPhone5,2
Process: myapp [611]
Path: /var/mobile/Applications/40D6D77C-1DBB-4F6B-BEE1-73A67C789C49/myapp.app/myapp
Identifier: com.myapp
Version: 1.0 (0.9)
Code Type: ARM (Native)
Parent Process: launchd [1]
Date/Time: 2013-10-17 11:16:45.559 +0530
OS Version: iOS 7.0.2 (11A501)
Report Version: 104
Exception Type: EXC_CRASH (SIGTRAP)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Triggered by Thread: 0
Last Exception Backtrace:
0 CoreFoundation 0x2fc9fe86 __exceptionPreprocess + 126
1 libobjc.A.dylib 0x39f9a6c2 objc_exception_throw + 34
2 CoreFoundation 0x2fc9f974 __NSFastEnumerationMutationHandler + 124
3 Foundation 0x30604f32 -[NSISEngine substituteOutAllOccurencesOfBodyVar:withExpression:] + 438
4 Foundation 0x30607ba2 -[NSISEngine pivotToMakeBodyVar:newHeadOfRowWithHead:andDropRow:] + 334
5 Foundation 0x3060594c -[NSISEngine minimizeConstantInObjectiveRowWithHead:] + 232
6 Foundation 0x3060546e -[NSISEngine optimize] + 170
7 Foundation 0x306011a8 -[NSISEngine withBehaviors:performModifications:] + 312
8 UIKit 0x32424490 -[UIView(Hierarchy) _postMovedFromSuperview:] + 292
9 UIKit 0x3243114e -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1398
10 UIKit 0x32447a9c -[UIView(Hierarchy) insertSubview:atIndex:] + 32
11 UIKit 0x325fb888 -[UINavigationBar _wrapView:inClippingViewWithLeftBoundary:rightBoundary:leftMaskImage:leftMaskIsChevron:rightMaskImage:] + 240
12 UIKit 0x325b505e -[UINavigationBar _startPopAnimationFromItems:fromBarStyle:toItems:toBarStyle:] + 1982
13 UIKit 0x324f1b88 -[UINavigationBar popNavigationItem] + 1316
14 UIKit 0x324f14a0 -[UINavigationBar _popNavigationItemWithTransition:] + 556
15 UIKit 0x326f02ac ___popViewControllerNormal_block_invoke + 152
16 UIKit 0x324d43a0 -[UINavigationController _startDeferredTransitionIfNeeded:] + 868
17 UIKit 0x324d3fe4 -[UINavigationController __viewWillLayoutSubviews] + 40
18 UIKit 0x324d3f78 -[UILayoutContainerView layoutSubviews] + 180
19 UIKit 0x3242552e -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 342
20 QuartzCore 0x320acf3e -[CALayer layoutSublayers] + 138
21 QuartzCore 0x320a8762 CA::Layer::layout_if_needed(CA::Transaction*) + 346
22 QuartzCore 0x320a85f4 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 12
23 QuartzCore 0x320a8008 CA::Context::commit_transaction(CA::Transaction*) + 224
24 QuartzCore 0x320a7e1a CA::Transaction::commit() + 310
25 QuartzCore 0x320d5436 CA::Transaction::release_thread(void*) + 158
26 libsystem_pthread.dylib 0x3a5af9b0 _pthread_tsd_cleanup + 160
27 libsystem_pthread.dylib 0x3a5af732 _pthread_exit + 82
28 libsystem_pthread.dylib 0x3a5b04b8 pthread_exit + 24
29 Foundation 0x305d7ac6 +[NSThread exit] + 6
30 Foundation 0x30683de0 __NSThread__main__ + 1088
31 libsystem_pthread.dylib 0x3a5b0c58 _pthread_body + 136
32 libsystem_pthread.dylib 0x3a5b0bca _pthread_start + 98
33 libsystem_pthread.dylib 0x3a5aeccc thread_start + 4
Thread 0 Crashed:
0 libsystem_malloc.dylib 0x3a572596 szone_free_definite_size + 1510
1 UIFoundation 0x3754aab4 -[NSAttributeDictionaryEnumerator dealloc] + 68
2 libobjc.A.dylib 0x39fa5b06 objc_object::sidetable_release(bool) + 170
3 libobjc.A.dylib 0x39f9701e (anonymous namespace)::AutoreleasePoolPage::pop(void*) + 354
4 QuartzCore 0x320a1b54 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 64
5 CoreFoundation 0x2fc6af6e __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 18
6 CoreFoundation 0x2fc688fa __CFRunLoopDoObservers + 282
7 CoreFoundation 0x2fc68c46 __CFRunLoopRun + 734
8 CoreFoundation 0x2fbd353c CFRunLoopRunSpecific + 520
9 CoreFoundation 0x2fbd331e CFRunLoopRunInMode + 102
10 GraphicsServices 0x3490a2e6 GSEventRunModal + 134
11 UIKit 0x3248a1e0 UIApplicationMain + 1132
12 myapp 0x000aac16 main (main.mm:16)
13 libdyld.dylib 0x3a493ab4 start + 0
Thread 1:
0 libsystem_kernel.dylib 0x3a537838 kevent64 + 24
1 libdispatch.dylib 0x3a4860d0 _dispatch_mgr_invoke + 228
2 libdispatch.dylib 0x3a48063e _dispatch_mgr_thread + 34
Thread 2 name: com.apple.NSURLConnectionLoader
Thread 2:
0 libsystem_kernel.dylib 0x3a537a84 mach_msg_trap + 20
1 libsystem_kernel.dylib 0x3a53787c mach_msg + 36
2 CoreFoundation 0x2fc6a55c __CFRunLoopServiceMachPort + 152
3 CoreFoundation 0x2fc68c7c __CFRunLoopRun + 788
4 CoreFoundation 0x2fbd353c CFRunLoopRunSpecific + 520
5 CoreFoundation 0x2fbd331e CFRunLoopRunInMode + 102
6 Foundation 0x3060e64c +[NSURLConnection(Loader) _resourceLoadLoop:] + 316
7 Foundation 0x30683dc2 __NSThread__main__ + 1058
8 libsystem_pthread.dylib 0x3a5b0c5a _pthread_body + 138
9 libsystem_pthread.dylib 0x3a5b0bca _pthread_start + 98
10 libsystem_pthread.dylib 0x3a5aeccc thread_start + 4
Thread 3 name: com.apple.CFSocket.private
Thread 3:
0 libsystem_kernel.dylib 0x3a54a440 select$DARWIN_EXTSN + 20
1 CoreFoundation 0x2fc6e45e __CFSocketManager + 482
2 libsystem_pthread.dylib 0x3a5b0c5a _pthread_body + 138
3 libsystem_pthread.dylib 0x3a5b0bca _pthread_start + 98
4 libsystem_pthread.dylib 0x3a5aeccc thread_start + 4
[12:37:06 PM] Devika Deshmukh: Thread 4:
0 libsystem_kernel.dylib 0x3a537a84 mach_msg_trap + 20
1 libsystem_kernel.dylib 0x3a53787c mach_msg + 36
2 CoreFoundation 0x2fc6a55c __CFRunLoopServiceMachPort + 152
3 CoreFoundation 0x2fc68c7c __CFRunLoopRun + 788
4 CoreFoundation 0x2fbd353c CFRunLoopRunSpecific + 520
5 CoreFoundation 0x2fbd331e CFRunLoopRunInMode + 102
6 Foundation 0x305c1822 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 250
7 Foundation 0x30612664 -[NSRunLoop(NSRunLoop) run] + 76
8 myapp 0x00197bdc +[AFURLConnectionOperation networkRequestThreadEntryPoint:] (AFURLConnectionOperation.m:160)
9 Foundation 0x30683dc2 __NSThread__main__ + 1058
10 libsystem_pthread.dylib 0x3a5b0c5a _pthread_body + 138
11 libsystem_pthread.dylib 0x3a5b0bca _pthread_start + 98
12 libsystem_pthread.dylib 0x3a5aeccc thread_start + 4
Thread 5:
0 libsystem_c.dylib 0x3a4fb09e __abort + 102
1 libsystem_c.dylib 0x3a4fb034 abort + 84
2 myapp 0x001bd8ea ___lldb_unnamed_function5196$$myapp + 22
3 CoreFoundation 0x2fca018a __handleUncaughtException + 578
4 libobjc.A.dylib 0x39f9a924 _objc_terminate() + 172
5 libc++abi.dylib 0x399601b0 std::__terminate(void (*)()) + 76
6 libc++abi.dylib 0x3995fa04 __cxa_throw + 112
7 libobjc.A.dylib 0x39f9a796 objc_exception_throw + 246
8 CoreFoundation 0x2fc9f974 __NSFastEnumerationMutationHandler + 124
9 Foundation 0x30604f32 -[NSISEngine substituteOutAllOccurencesOfBodyVar:withExpression:] + 438
10 Foundation 0x30607ba2 -[NSISEngine pivotToMakeBodyVar:newHeadOfRowWithHead:andDropRow:] + 334
11 Foundation 0x3060594c -[NSISEngine minimizeConstantInObjectiveRowWithHead:] + 232
12 Foundation 0x3060546e -[NSISEngine optimize] + 170
13 Foundation 0x306011a8 -[NSISEngine withBehaviors:performModifications:] + 312
14 UIKit 0x32424490 -[UIView(Hierarchy) _postMovedFromSuperview:] + 292
15 UIKit 0x3243114e -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1398
16 UIKit 0x32447a9c -[UIView(Hierarchy) insertSubview:atIndex:] + 32
17 UIKit 0x325fb888 -[UINavigationBar _wrapView:inClippingViewWithLeftBoundary:rightBoundary:leftMaskImage:leftMaskIsChevron:rightMaskImage:] + 240
18 UIKit 0x325b505e -[UINavigationBar _startPopAnimationFromItems:fromBarStyle:toItems:toBarStyle:] + 1982
19 UIKit 0x324f1b88 -[UINavigationBar popNavigationItem] + 1316
20 UIKit 0x324f14a0 -[UINavigationBar _popNavigationItemWithTransition:] + 556
21 UIKit 0x326f02ac ___popViewControllerNormal_block_invoke + 152
22 UIKit 0x324d43a2 -[UINavigationController _startDeferredTransitionIfNeeded:] + 870
23 UIKit 0x324d3fe4 -[UINavigationController __viewWillLayoutSubviews] + 40
24 UIKit 0x324d3f78 -[UILayoutContainerView layoutSubviews] + 180
25 UIKit 0x3242552e -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 342
26 QuartzCore 0x320acf3e -[CALayer layoutSublayers] + 138
27 QuartzCore 0x320a8762 CA::Layer::layout_if_needed(CA::Transaction*) + 346
28 QuartzCore 0x320a85f4 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 12
29 QuartzCore 0x320a8008 CA::Context::commit_transaction(CA::Transaction*) + 224
30 QuartzCore 0x320a7e1a CA::Transaction::commit() + 310
31 QuartzCore 0x320d5436 CA::Transaction::release_thread(void*) + 158
32 libsystem_pthread.dylib 0x3a5af9b2 _pthread_tsd_cleanup + 162
33 libsystem_pthread.dylib 0x3a5af732 _pthread_exit + 82
34 libsystem_pthread.dylib 0x3a5b04b8 pthread_exit + 24
35 Foundation 0x305d7ac6 +[NSThread exit] + 6
36 Foundation 0x30683de0 __NSThread__main__ + 1088
37 libsystem_pthread.dylib 0x3a5b0c5a _pthread_body + 138
38 libsystem_pthread.dylib 0x3a5b0bca _pthread_start + 98
39 libsystem_pthread.dylib 0x3a5aeccc thread_start + 4
Thread 6:
0 libsystem_kernel.dylib 0x3a54ac7c __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x3a5aee06 _pthread_wqthread + 306
2 libsystem_pthread.dylib 0x3a5aecc0 start_wqthread + 4
Thread 0 crashed with ARM Thread State (32-bit):
r0: 0x00280a00 r1: 0xfffff000 r2: 0x17f9a000 r3: 0x0000000c
r4: 0x17f99650 r5: 0x3c32fe08 r6: 0x3c32fe00 r7: 0x27d5cb50
r8: 0x00000001 r9: 0x00000fff r10: 0x17f99650 r11: 0x0000008a
ip: 0x17f99db0 sp: 0x27d5cb4c lr: 0x39f96e39 pc: 0x3a572596
cpsr: 0x20000030
更新
以下是我们填充数据源的代码：
(void) viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
viewWillAppearFlag = true;
if(dataFetched) {
[self setupDatasourceDetails:self.myData];
}
}
(void) setupDatasourceDetails:(NSArray *)data {
self.datasource = [MyDatasource new];
self.datasource.data=data;
[self.myTable setDataSource:self.datasource];
[self.myTable setDelegate:self.datasource];
[self.myTable reloadData];
}
//Callback from REST services
(void) onDataFetched:(NSArray *)data{
dataFetched=true;
self.myData=data;
if(viewWillAppearFlag){
[self setupDatasourceDetails:self.myData]; //the event which will occur later(either viewWillAppear or dataFetched) calls setupDatasourceDetails
}
}
更新
从一个视图控制器转换回另一个视图控制器（在导航控制器中）时发生错误。
我们正在使用[self.navigationController popViewControllerAnimated：YES];转换回上一个视图控制器。转换发生在主线程上。
如果需要更多信息，请告知我们。
更新
我们的问题似乎已经解决了。我们将功能从viewWillAppear移到了viewDidAppear。这个修复似乎解决了这个问题。有谁知道这个修复工作的原因？请告诉我们。感谢。
答案 0 :(得分：2)
两个建议：
strong属性（不是
weak）（以及MyDatasource上的数据属性）确保
在主队列上调用onDataFetched:。如果不确定，请使用此功能
调度机制改为：
dispatch_async(dispatch_get_main_queue(), ^{
// all update code here
});
答案 1 :(得分：1)
我不认为错误直接出现在您发布的代码中，但是：
NSFastEnumerationMutationHandler
。 例如，这是错误的：
for ( id obj in anArray ) {
if ( [obj shouldRemove == YES ) {
[anArray removeObject:obj];
}
}
如果您需要这样做，您应该使用数组的副本或使用filteredArrayUsingPredicate。
答案 2 :(得分：-1)
无法查看所有代码，但我认为您需要在设置约束之前调用layoutIfNeeded，因为在ViewWillAppear之前未计算视图。它在ViewDidAppear中成功的事实是因为已经计算了元素。或者，您可以在DidLayoutSubviews中尝试您的代码。