iphone - 无法找到 iOS 错误访问

Question

这么多小时以来，我一直被一个愚蠢的错误访问所困扰。我完全找不到它。我希望你们中的一些人能够向我展示答案。在下面的代码中，它出现在行中:NSString * stringCallVisit = [[NSString alloc]initWithFormat:.....我无法理解，除了参数 theIntervention 之外，所有对象都是方法的局部对象。

如果我注释方法 NSString * stringCallVisit = [[NSString alloc]initWithFormat:... 即使我执行 id obj = callVisit.injectionby; 也不会出现错误访问； 而不是；所以我认为错误的访问不是来自 callVisit 对象，而是来自 stringCallVisit 对象。但为什么我只是在出现错误访问的尖齿上实例化它。

谢谢你的帮助，

-(NSString*)getCallVisitForIntervention:(Intervention*)theIntervention
{

NSManagedObjectContext *context = [iPad_TestAppDelegate mainContext];
NSError *error;

NSFetchRequest *requestCallVisit = [[NSFetchRequest alloc]init];
[requestCallVisit setEntity:[NSEntityDescription entityForName:@"CallVisit" inManagedObjectContext:context]];

NSPredicate *predicateInterventionID = [NSPredicate predicateWithFormat:@"intervention_id = %@",theIntervention.id];
[requestCallVisit setPredicate:predicateInterventionID];        

NSMutableArray *callVisits = [[context executeFetchRequest:requestCallVisit error:&error]mutableCopy];



NSString *xml  = @"<CallVisits>";

for(CallVisit *callVisit in callVisits) 
{

    NSString * stringCallVisit = [[NSString alloc]initWithFormat:
                                  @"<CallVisit>"
                                  "<id>%@</id>"
                                  "<injectionby>%@</injectionby>"
                                  "<injectionspot>%@</injectionspot>"
                                  "<intervention_id>%@</intervention_id>"
                                  "<fls>%d</fls>"
                                  "<weight>%d</weight>"
                                  "<height>%d</height>"
                                  "<painAtInjection>%d</painAtInjection>"
                                  "<created>%@</created>"
                                  "<siteReaction>%d</siteReaction>"
                                  "<technicalComplain>%d</technicalComplain>"
                                  "<field1>%d</field1>"
                                  "<field2>%d</field2>"
                                  "<riskCompliance>%d</riskCompliance>"
                                  "<reasonCompliance>%@</reasonCompliance>"
                                  "<placebo>%@</placebo>"
                                  "<needlereceived>%@</needlereceived>"
                                  "<compliance>%d</compliance>"
                                  "<psychologicalCondition>%d</psychologicalCondition>"
                                  "<keepsegment>%d</keepsegment>"
                                  "</CallVisit>",
                                  callVisit.id,
                                  callVisit.injectionby,
                                  callVisit.injectionspot,
                                  callVisit.intervention_id,
                                  [callVisit.fls doubleValue],
                                  [callVisit.weight doubleValue],
                                  [callVisit.height doubleValue],
                                  [callVisit.painAtInjection intValue],
                                  callVisit.created,
                                  [callVisit.siteReaction intValue],
                                  [callVisit.technicalComplain intValue],
                                  [callVisit.field1 intValue],
                                  [callVisit.field2 intValue],
                                  [callVisit.riskCompliance intValue],
                                  callVisit.reasonCompliance,
                                  callVisit.placebo,
                                  callVisit.needlereceived,
                                  [callVisit.compliance intValue],
                                  [callVisit.psychologicalCondition intValue],
                                  [callVisit.keepsegment intValue]];



    xml = [xml stringByAppendingString:stringCallVisit];
    [stringCallVisit release];

    id obj = callVisit;

}       
[callVisits release];
[requestCallVisit release];

xml = [xml stringByAppendingString:@"</CallVisits>"];

return xml;
}

编辑:

我按照你说的做了，但我无法理解日志，而且我没有收到信息 malloc 的地址。我有点迷路:)

编辑这是日志。但这很奇怪，但知道应用程序在其他地方崩溃了。

GuardMalloc[iPad Test-7405]: Failed to VM allocate 397648 bytes
GuardMalloc[iPad Test-7405]: Explicitly trapping into debugger!!!
sharedlibrary apply-load-rules all
Error in re-setting breakpoint 1:
Catchpoint 2 (throw)iPad Test(7405,0xaccab2c0) malloc: recording malloc stacks to disk using standard recorder
GuardMalloc[iPad Test-7405]: *** mmap(size=2097152) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
GuardMalloc[iPad Test-7405]: *** mmap(size=2097152) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
No memory available to program: call to malloc failed
Error in re-setting breakpoint 1:
Error in re-setting breakpoint 1:
GuardMalloc[iPad Test-7405]: *** mmap(size=2097152) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
Current language:  auto; currently objective-c
GuardMalloc[iPad Test-7405]: *** mmap(size=2097152) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
No memory available to program: call to malloc failed
GuardMalloc[iPad Test-7405]: *** mmap(size=2097152) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
No memory available to program: call to malloc failed
GuardMalloc[iPad Test-7405]: *** mmap(size=2097152) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
No memory available to program: call to malloc failed
(gdb) 

Answer 1

设置NSZombieEnabled , MallocStackLogging , 和 guard malloc在调试器中。然后，当您的应用程序崩溃时，在 gdb 控制台中输入:

(gdb) info malloc-history 0x543216

将 0x543216 替换为导致崩溃的对象的地址，您将获得更有用的堆栈跟踪，它应该可以帮助您查明代码中导致问题的确切行.

See this article for more detailed instructions.

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编辑:看起来您可能内存不足。您是否实现了 didReceiveMemoryWarning 方法？如果是这样，请将 NSLog 放入其中以查明您是否内存不足。