ios - 抛出 'NSException' 实例后调用终止

Question

我尝试运行我的应用程序，但抛出了异常，在控制台中我得到了这个:

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) 

我注意到我得到了这一点，因为我尝试在我的 map View 中使用注释，请帮忙，提前谢谢:)

编辑

这是我的 for 循环，它可能会产生问题:

 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

异常的给定原因是“集合...在枚举时发生了变异”。这意味着您尝试在 for( in ) 循环中更改数组，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。如果查看调用堆栈的顶部，您会发现异常发生在 -[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，您应该很容易找到问题。

如果您想在使用快速枚举时修改数组，有两种可能性:跟踪您想要更改的所有内容(即要删除的索引列表)并在循环后进行更改，或者执行对数组的副本进行枚举。下面是第二种方法的示例:

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