终止所谓的“NSException”

Question

我尝试运行我的应用程序，但我有抛出异常，在控制台中我有这样的：

2011-05-05 00:18:50.984 myApp[2906:207] *** Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <__NSArrayM: 0x6b8b780> was mutated while being enumerated.(
    "<MyLocation: 0x6b67af0>", 
    "<MyLocation: 0x6b19360>", 
    "<MyLocation: 0x6b67a70>", 
    "<MyLocation: 0x6b8d110>", 
    "<MyLocation: 0x6b8d280>", 
    "<MyLocation: 0x6b8ce50>", 
    "<MyLocation: 0x6b8d660>" 
)' 
*** Call stack at first throw: 
(
    0 CoreFoundation      0x02915919 __exceptionPreprocess + 185 
    1 libobjc.A.dylib      0x0272a5de objc_exception_throw + 47 
    2 CoreFoundation      0x029153d9 __NSFastEnumerationMutationHandler + 377 
    3 myApp       0x00005755 -[StationsSurLaCarteViewController requestFinished:] + 343 
    4 myApp       0x000195cb -[ASIHTTPRequest reportFinished] + 171 
    5 Foundation       0x000abe9a __NSThreadPerformPerform + 251 
    6 CoreFoundation      0x028f6d7f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15 
    7 CoreFoundation      0x028552cb __CFRunLoopDoSources0 + 571 
    8 CoreFoundation      0x028547c6 __CFRunLoopRun + 470 
    9 CoreFoundation      0x02854280 CFRunLoopRunSpecific + 208 
    10 CoreFoundation      0x028541a1 CFRunLoopRunInMode + 97 
    11 GraphicsServices     0x02e8e2c8 GSEventRunModal + 217 
    12 GraphicsServices     0x02e8e38d GSEventRun + 115 
    13 UIKit        0x0033ab58 UIApplicationMain + 1160 
    14 myApp       0x0000224c main + 102 
    15 myApp       0x000021dd start + 53 
) 
terminate called after throwing an instance of 'NSException' 
Program received signal: “SIGABRT”. 
(gdb) 

我注意到，我得到了自我尝试使用标注为我的地图视图，请帮助，THX提前:)

编辑

这是我for循环，可以使问题：

for (int i=0; i<[array count]; i++) { 

      NSDictionary *stationEnCours=[array objectAtIndex:i]; 


      NSString *distance=[stationEnCours objectForKey:@"distance"]; 
      float lng = [[stationEnCours objectForKey:@"ssiphone_longitude"] floatValue]; 
      float lat = [[stationEnCours objectForKey:@"ssiphone_latitude"] floatValue]; 
      NSString *ensStation=[stationEnCours objectForKey:@"ssiphone_enseigne"]; 

      location2D = (CLLocationCoordinate2D){ .latitude = lat, .longitude = lng }; 
      MyLocation *annotation=[[[MyLocation alloc]initWithName:ensStation distanceVersLaStation:distance coordinate:location2D]autorelease]; 
      [mapView addAnnotation:annotation]; 
      MKCoordinateSpan span={latitudeDelta:0.2,longitudeDelta:0.2}; 
      MKCoordinateRegion region={location2D,span}; 
      [mapView setRegion:region]; 
      [self.view addSubview:mapView]; 
      }` 

Answer 1

您例外的给定原因是“集合...被列举时发生了变化”。这意味着您试图更改for(in)循环内的数组，这是不允许的，因为它会更改您应该枚举的对象。原因的结尾是您正在枚举的数组的转储。它包含7个MyLocation对象。如果您查看调用堆栈的顶部，您会发现异常发生在您的-[StationsSurLaCarteViewController requestFinished:]方法中。如果您仔细查看该方法并找到使用快速枚举的地方，则应该很容易找到问题所在。

如果要在使用快速枚举的同时修改数组，则有两种可能性：跟踪要更改的所有内容（即要删除的索引列表）并在循环后进行更改，或者请在数组的副本上进行枚举。这里是第二种方法的例子：

NSArray *copiedArray = [originalArray copy]; 
for(id theObject in copiedArray) { 
    if([theObject shouldBeDeleted]) { 
     [originalArray removeObject:theObject]; 
    } 
} 
[copiedArray release]; 

NSArray *copiedArray = [originalArray copy]; 
for(id theObject in copiedArray) { 
    if([theObject shouldBeDeleted]) { 
     [originalArray removeObject:theObject]; 
    } 
} 
[copiedArray release];