枚举时变异数组

Question

我得到的错误是

Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <CALayerArray: 0x7c85080> was mutated while being enumerated.'

我理解的NSGenericException是,我在枚举时从数组中删除了一些东西.仍然知道并环顾四周我似乎无法解决我的问题.这是下面的代码.

-(void)tableView(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
     //Checks if message has been read. If message has not it updates the unreadMessages array
     if ([unreadMessage containsObject:[NSString stringWithFormat:@"m%@",[[storage_array objectAtIndex:indexPath.row] objectForKey:@"id"]]] == TRUE && [[[storage_array objectAtIndex:indexPath.row] objectForKey:@"itemtype"] isEqualToString:@"message"]  == TRUE){

     //Unread
     [unreadMessage removeObject:[NSString stringWithFormat:@"m%@",[[storage_array objectAtIndex:indexPath.row] objectForKey:@"id"]]];
     [unreadMessage writeToFile:[self saveUnreadMessages] atomically:YES];
     //Read
     [readMessage addObject:[NSString stringWithFormat:@"m%@",[[storage_array objectAtIndex:indexPath.row] objectForKey:@"id"]]];
     [readMessage writeToFile:[self saveReadMessages] atomically:YES];
     [tableView reloadData];
 }
 else if ([unreadNewsletter containsObject:[NSString stringWithFormat:@"n%@",[[storage_array objectAtIndex:indexPath.row] objectForKey:@"id"]]] == TRUE && [[[storage_array objectAtIndex:indexPath.row] objectForKey:@"itemtype"] isEqualToString:@"newsletter"]  == TRUE){

     //Unread
     [unreadNewsletter removeObject:[NSString stringWithFormat:@"n%@",[[storage_array objectAtIndex:indexPath.row] objectForKey:@"id"]]];
     [unreadNewsletter writeToFile:[self saveUnreadNewsletters] atomically:YES];
     //Read
     [readNewsletter addObject:[NSString stringWithFormat:@"n%@",[[storage_array objectAtIndex:indexPath.row] objectForKey:@"id"]]];
     [readNewsletter writeToFile:[self saveReadNewsletters] atomically:YES];
     [tableView reloadData];
 }
}

Answer 1

您不应该修改您正在迭代的数组.如果您打算这样做,您应该迭代它的副本:

for (id item in [array copy])
{
    …
}

(使用ARC.[[array copy] autorelease]没有ARC.)

如果需要,您可以在执行任何操作之前检查该项是否仍在可变数组中.