解决报错libc++abi.dylib: terminate_handler unexpectedly threw an exception

libc++abi.dylib是一个动态库，动态错误一般是由动态错误引起。
for(NSMutableDictionary *downloadInfo in downloadingArray)
{
if ([[downloadInfo objectForKey:kMZDownloadKeyFileName] isEqual:s9id])
{

NSURLSessionDownloadTask *downloadTask = [downloadInfo objectForKey:kMZDownloadKeyTask];
NSString *downloadingStatus = [downloadInfo objectForKey:kMZDownloadKeyStatus];
NSInteger indexOfObject = [downloadingArray indexOfObject:downloadInfo];
if([downloadingStatus isEqualToString:RequestStatusDownloading])
{
[downloadTask suspend];
[downloadInfo setObject:RequestStatusPaused forKey:kMZDownloadKeyStatus];
[downloadInfo setObject:[NSDate date] forKey:kMZDownloadKeyStartTime];

[downloadingArray replaceObjectAtIndex:indexOfObject withObject:downloadInfo];

}
}
}以上是我在运行过程中崩溃的地方，在遍历的过程中数据突然发生变化产生的错误，要把参照数据源和要修改的数据源分开才不会发生异常，
解决如下：

NSMutableArray *tempArray = [downloadingArray copy];
for(NSMutableDictionary *downloadInfo in tempArray)
{
if ([[downloadInfo objectForKey:kMZDownloadKeyFileName] isEqual:s9id])
{

NSURLSessionDownloadTask *downloadTask = [downloadInfo objectForKey:kMZDownloadKeyTask];
NSString *downloadingStatus = [downloadInfo objectForKey:kMZDownloadKeyStatus];
NSInteger indexOfObject = [tempArray indexOfObject:downloadInfo];
if([downloadingStatus isEqualToString:RequestStatusDownloading])
{
[downloadTask suspend];
[downloadInfo setObject:RequestStatusPaused forKey:kMZDownloadKeyStatus];
[downloadInfo setObject:[NSDate date] forKey:kMZDownloadKeyStartTime];

[downloadingArray replaceObjectAtIndex:indexOfObject withObject:downloadInfo];

}
}
}