Objective c 由于NSX操作（QOS、服务质量）在OS X Yosemite上应用程序崩溃

我的应用程序在OS X Yosemite上不断崩溃，原因如下： 崩溃线程：7调度队列：NSOperationQueue 0x60800239D80:：NSOperation 0x60000013b3a0（QOS:实用程序）

将我的操作更改为：

if ([self respondsToSelector:@selector(qualityOfService)]) {
    self.qualityOfService = NSQualityOfServiceUtility;
}

但应用程序不断崩溃。 崩溃线程的堆栈跟踪：

线程7崩溃：：调度队列：NSOperationQueue 0x60800239D80:： NSOperation 0x60000013b3a0（QOS:实用程序）

0 libobjc.A.dylib 0x00007fff8af4f0dd objc_msgSend+ 二十九

1 com.apple.CoreText 0x00007fff882d0ce7 TatAttributes:：ParseAttributes（uu CFDictionary const*，void const*&， TInlineVector，30ul>&）+521

2 com.apple.CoreText 0x00007fff882d06f9 TatAttributes:：TatAttributes（uu CFDictionary const*）+257

3 com.apple.CoreText 0x00007fff882e8295 TRunEncoder:：Encode（_CTGlyphStorage*，CFRange，unsigned int， __CFC字典常数*）+85

4 com.apple.CoreText 0x00007fff882e8231 CtrunCreateMatableRunswithStorageandOptions+191

5 com.apple.ui基金会0x00007fff8f0f329e -[NSATGlyph存储createCTTypesetter]+705

6 com.apple.ui基金会0x00007fff8f0ecf0c -[NSATSTTypesetter\ctTypesetter]+324

7 com.apple.ui基金会0x00007fff8f0f78b5 -[NSATSLineFragmentLayoutForStartingGlyphatIndex:characterIndex:minPosition:maxPosition:lineFragmentRect:] +89

8 com.apple.ui基金会0x00007fff8f0edd43 -[NSATSTTypesetter\u LayoutLineFragmentStartingwithGlyphatinex:characterIndex:atPoint:renderingContext:] +2901 9 com.apple.UIFoundation 0x00007fff8f0efa08-[NSATS排字机布局段落点：][156

10 com.apple.ui基金会0x00007fff8f040356-[NSTypesetter _layoutGlyphsInLayoutManager:startingAtGlyphIndex:maxNumberOfLineFragments:maxCharacterIndex:nextGlyphIndex:nextCharacterIndex:] +4713

11 com.apple.ui基金会0x00007fff8f041ae5-[NSTypesetter LayoutCharactersRange:forLayoutManager:maximumNumberOfLineFragments:] +246

12 com.apple.ui基金会0x00007FFF8F0743 -[NSATSTTypeSetter LayoutCharactersRange:forLayoutManager:maximumNumberOfLineFragments:] +967

13 com.apple.ui基金会0x00007fff8f0b9e76 -[NSLayoutManager（NSPrivate）\为字符范围填写LayoutAuthole:desiredNumberOfLines:isSoft:+1334

14 com.apple.ui基金会0x00007fff8f0c370c _NSFASTFILLLLAYOUTHOLESFORGLYPHRANGE+1493

15 com.apple.ui基金会0x00007fff8f0c8e54 -[NSLayoutManager（NSPrivate）\u退税依据范围：点：:+542

16 com.apple.AppKit 0x00007fff8f37fc15-[NSTextView drawRect:+1878

17 com.apple.AppKit 0x00007fff8f37f409 -[NSTextView（NSTextView\U LAYERBACK）绘图层：inGraphicsContext:+493

18 com.apple.AppKit 0x00007fff8f332980 +[NSGraphicsContext配置GraphicsContextForCalayer:withCGContext:AndEnderWithHandler:] +97

19 com.apple.QuartzCore 0x00007fff92e70153 CABackingStoreUpdate+3306

20 com.apple.QuartzCore 0x00007fff92e6f463 ___ZN2CA5layer8显示模块调用+59

21 com.apple.QuartzCore 0x00007fff92e6f41f x__分配+81

22 com.apple.QuartzCore 0x00007fff92e6ef1c CA:：Layer:：display_uz（）+1546

23 com.apple.AppKit 0x00007fff8f31c89f _NSBackingLayerDisplay+617

24 com.apple.QuartzCore 0x00007fff92e6e641 CA:：Layer:：需要时显示（CA:：事务*）+603

25 com.apple.QuartzCore 0x00007fff92e6dd7d CA：：图层：：布局和显示（如果需要）（CA：：事务*）+35

26 com.apple.QuartzCore 0x00007fff92e6d50e CA:：Context:：commit_事务（CA:：transaction*）+242

27 com.apple.QuartzCore 0x00007fff92e6d164 CA:：事务：：提交（）+390

28 com.apple.QuartzCore 0x00007fff92e7df55 CA:：Transaction:：observer\u回调（\uu CFRunLoopObserver*，未签名 长，空*）+71

29 com.apple.CoreFoundation 0x00007fff902bdd87 CFRUNLOOP\u正在调用一个回调函数

30 com.apple.CoreFoundation 0x00007fff902bdce0 __cfrunloopdoobserver+368

31 com.apple.CoreFoundation 0x00007fff902af858 CFRunLoopRunSpecific+328

32 -[nsrunlop（nsrunlop）运行模式：beforeDate:+278

33 com.pack.MyApp 0x000000010ab54d5b-[同步操作] 开始]+886

＜P＞34 +184

35 libdispatch.dylib 0x00007fff925e9c13 _调度客户呼叫+8

36 libdispatch.dylib 0x00007fff925ed365 _调度队列排液+1100

37 libdispatch.dylib 0x00007fff925eeecc _调度队列调用+202

38 libdispatch.dylib 0x00007fff925ec6b7 _调度\u根\u队列\u排水+463

39 libdispatch.dylib 0x00007fff925fafe4 _调度工人线程3+91

40 libsystem_pthread.dylib 0x00007fff8596d6cb _pthread_wqthread+729

41 libsystem_pthread.dylib 0x00007fff8596b4a1启动_wqthread+ 十三,

谢谢大家!