崩溃在actionForLayer：forKey： [英] Crash in actionForLayer:forKey:
问题描述
在更改某些UILabel的帧时，我有一个神秘的EXC_BAD_ACCESS。崩溃是随机的，通常我必须重复几分钟的条件。
I have a cryptic EXC_BAD_ACCESS when changing some UILabel's frame. The crash is random, usually I have to repeat the conditions for several minutes.
启用NSZombies以及其他内存调试标志（NSDebugEnabled，MallocStackLogging），帮助，崩溃仍然保持不透明：只是一个BAD_ACCESS，控制台中没有消息。目标似乎是正确和活跃的，因此它看起来不像是一个解除分配的内存问题。
Enabling NSZombies, as well as other memory debug flags (NSDebugEnabled, MallocStackLogging), doesn't help, the crash stills stays as opaque : just a BAD_ACCESS with no message in the console. The target seems correct and alive, so it doesn't look like a deallocated memory problem.
为了获得更多信息，我将UILabel子类化并重写了崩溃函数：
To get some more info, I subclassed UILabel and rewrote the crashing function :
@implementation TestUILabel
- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event {
return [super actionForLayer:layer forKey:event];
}
@end
它在超级方法中崩溃，但在检查时一切似乎都正确（打印retainCount为'self'和'layer'分别给出3和2）：
It crashes in the super's method, but on inspection everything seems correct (printing retainCount for 'self' and 'layer' gives respectively 3 and 2) :
（gdb）po self
(gdb) po self
< TestUILabel：0x6ac2800;
baseClass = UILabel; frame =（173 174;
0 0）; text ='54m²'; opaque = NO;
autoresize = LM + TM;
autoresizesSubviews = NO;
userInteractionEnabled = NO;
动画= {
position =< CABasicAnimation：
0xe07ba60>; }; layer =< CALayer：
0xbf1b950 >>
< TestUILabel: 0x6ac2800; baseClass = UILabel; frame = (173 174; 0 0); text = '54 m²'; opaque = NO; autoresize = LM+TM; autoresizesSubviews = NO; userInteractionEnabled = NO; animations = { position=< CABasicAnimation: 0xe07ba60>; }; layer = < CALayer: 0xbf1b950>>
（gdb）po event
(gdb) po event
bounds
（gdb）po layer
(gdb) po layer
< CALayer的：0xbf1b950;
position = CGPoint（173 174）; bounds =
CGRect（0 0; 0 0）; delegate =
< TestUILabel：0x6ac2800; baseClass =
UILabel; frame =（173 174; 0 0）;文字
='54m²'; opaque = NO; autoresize = LM + TM; autoresizesSubviews = NO;
userInteractionEnabled = NO;
动画= {
position =< CABasicAnimation：
0xe07ba60>; }; layer =< CALayer：
0xbf1b950 >>; contents =< CGImage
0xe04ed60>; opacity = 1;动画=
[position =< CABasicAnimation：
0xe07ba60>]>
< CALayer:0xbf1b950; position = CGPoint (173 174); bounds = CGRect (0 0; 0 0); delegate = < TestUILabel: 0x6ac2800; baseClass = UILabel; frame = (173 174; 0 0); text = '54 m²'; opaque = NO; autoresize = LM+TM; autoresizesSubviews = NO; userInteractionEnabled = NO; animations = { position=< CABasicAnimation: 0xe07ba60>; }; layer = < CALayer: 0xbf1b950>>; contents = < CGImage 0xe04ed60>; opacity = 1; animations = [position=< CABasicAnimation: 0xe07ba60>]>
是否有人遇到类似的问题？或者有什么想法可以来自哪里？
Did someone get a similar problem ? Or have any ideas where this could come from ?
提前致谢！
编辑：
这是完整的崩溃回溯：
here's the complete crash backtrace :
线程1，队列：
com.apple.main-thread
＃0 0x00459b2c in - [UIView（CALayerDelegate）actionForLayer：forKey：]（）
＃1 0x00eaaac7 in - [CALayer actionForKey：]（）
＃2 0x00ea80fe in actionForKey（CALayer *，
CA :: Transaction *，NSString *）（）
＃3 0x00ea8066 in beginChange（CALayer *，CA :: Transaction *，unsigned int，
objc_object *&）（）
＃4 0x00eaba3a在CALayerSetPosition（CALayer *，
CA :: Vec2 const&，bool）（）
＃5 0x00eab8b5 in - [CALayer setPosition：]（）
＃6 0x00eab7cc in - [CALayer setFrame：]（）
＃7 0x0045739d in - [UIView（Geometry）setFrame：]（）
＃8 0x00542a68 in - [UILabel setFrame：]（）
＃9 0x0000a97f in - [MosaicElementView setupWithAdvert：] at
/ Users / ei no / Prog / AJ / Classes / Search / SubViews / MosaicElementView.m：30
＃10 0x00079cb9 in - [SearchResultsViewController setupElement：withCell：indexPath：actualIndex：]
（）
＃11 0x000797a2 in - [SearchResultsViewController tableView：cellForRowAtIndexPath：]（）
＃12 0x004957fa in - [UITableView（UITableViewInternal）_createPreparedCellForGlobalRow：withIndexPath：]
（）
＃13 0x0048b77f in - [UITableView（UITableViewInternal）_createPreparedCellForGlobalRow：]（）
＃14 0x004a0450 in - [UITableView（_UITableViewPrivate）_updateVisibleCellsNow：]（）
＃15 0x00498538 in - [UITableView layoutSubviews]（）
＃16 0x00eb0451 in - [CALayer layoutSublayers]（）
＃17 0x00eb017c in CALayerLayoutIfNeeded（）
＃18 0x00ea937c in CA :: Context :: commit_transaction（CA :: Transaction *）
（）
＃19 0x00ea90d0 in CA :: Transaction :: commit（）（）
＃ 20 0x00ed97d5 in CA :: Transaction :: observer_callback（__ CFRunLoopObserver *，
unsigned long，void *）（）
＃21 0x017e9fbb in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
（）
＃22 0x0177f0e7 in __CFRunLoopDoObservers（）
＃23 0x01747bd7 in __CFRunLoopRun（）
＃24 0x01747240 in CFRunLoopRunSpecific（）
＃25 0x01747161 in CFRunLoopRunInMode（）
＃26 0x01e7d268 in GSEventRunModal （）
＃27 0x01e7d32d in GSEventRun（）
＃28 0x0043042e in UIApplicationMain（）
＃29 0x000021fe in main at / Users / eino / Prog / AJ / main.m:11
Thread 1, Queue :
com.apple.main-thread
#0 0x00459b2c in -[UIView(CALayerDelegate) actionForLayer:forKey:] ()
#1 0x00eaaac7 in -[CALayer actionForKey:] ()
#2 0x00ea80fe in actionForKey(CALayer*, CA::Transaction*, NSString*) ()
#3 0x00ea8066 in beginChange(CALayer*, CA::Transaction*, unsigned int, objc_object*&) ()
#4 0x00eaba3a in CALayerSetPosition(CALayer*, CA::Vec2 const&, bool) ()
#5 0x00eab8b5 in -[CALayer setPosition:] ()
#6 0x00eab7cc in -[CALayer setFrame:] ()
#7 0x0045739d in -[UIView(Geometry) setFrame:] ()
#8 0x00542a68 in -[UILabel setFrame:] ()
#9 0x0000a97f in -[MosaicElementView setupWithAdvert:] at /Users/eino/Prog/AJ/Classes/Search/SubViews/MosaicElementView.m:30
#10 0x00079cb9 in -[SearchResultsViewController setupElement:withCell:indexPath:actualIndex:] ()
#11 0x000797a2 in -[SearchResultsViewController tableView:cellForRowAtIndexPath:] ()
#12 0x004957fa in -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:withIndexPath:] ()
#13 0x0048b77f in -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:] ()
#14 0x004a0450 in -[UITableView(_UITableViewPrivate) _updateVisibleCellsNow:] ()
#15 0x00498538 in -[UITableView layoutSubviews] ()
#16 0x00eb0451 in -[CALayer layoutSublayers] ()
#17 0x00eb017c in CALayerLayoutIfNeeded ()
#18 0x00ea937c in CA::Context::commit_transaction(CA::Transaction*) ()
#19 0x00ea90d0 in CA::Transaction::commit() ()
#20 0x00ed97d5 in CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) ()
#21 0x017e9fbb in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#22 0x0177f0e7 in __CFRunLoopDoObservers ()
#23 0x01747bd7 in __CFRunLoopRun ()
#24 0x01747240 in CFRunLoopRunSpecific ()
#25 0x01747161 in CFRunLoopRunInMode ()
#26 0x01e7d268 in GSEventRunModal ()
#27 0x01e7d32d in GSEventRun ()
#28 0x0043042e in UIApplicationMain ()
#29 0x000021fe in main at /Users/eino/Prog/AJ/main.m:11
第9帧的删除线基本上只是帧的变化：
The crasing line from frame 9 is basically just the frame change :
labelPrice.frame = rect;
，其中rect是正确的CGRect（106,143,86,22）。
with rect being a correct CGRect (106, 143, 86, 22).
推荐答案
你可能已经检查了这个，但值得拍摄......
You probably already checked for this, but it's worth shot...
Are你确定你没有做任何会影响后台线程中任何UI元素的事情吗？也许你正在做一些与这个搜索相关的计算，它会改变某个视图的属性。
Are you certain that you aren't doing anything that would effect any UI elements in a background thread? Perhaps you're doing some computation related to this search and it changes a property of some view.
在我忘记了performSelectorOnMainThread的情况下，我看到了他的那种情况： withObject：waitUntilDone：调用然后在后台更改UI。
I have seen his sort of thing in cases where I forgot a performSelectorOnMainThread:withObject:waitUntilDone: call and then altered the UI in the background.
这篇关于崩溃在actionForLayer：forKey：的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
