在异步网络调用中使用inDatabase的正确方法是什么？

Question

当我成功地发布到服务器时，我使用AFNetworking和FMDB从数组中删除数据库行。我目前的问题是，我的日志记录显示我跳过了数组中的每一个项，所以我认为我在AFNetworking的异步请求中错误地使用了FMDB。

这就是代码的样子：

[manager POST:[_urlEndpoint absoluteString] parameters:data success:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"JSON: %@", responseObject);
    [_dbQueue inDatabase:^(FMDatabase *db) {
        for (int i = 0; i < arrayOfIds.count; ++i)
        {
            NSLog(@"Removing event at index: %@", arrayOfIds[i]);
            [_db removeWithId:arrayOfIds[i]];
        }
    }];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

在arrayOfIds中，日志显示我命中了1、2、3、skip 4等等。在这个特定的例子中，我确保只发送一个POST请求，这样就缩小了根本原因，所以我知道arrayOfIds没有多个访问。

我可能做错了什么，而我可能错过了？

(可能)我刚才问过的相关问题：FMDB: Does calling a method to make a query in the inDatabase block work the same way?

编辑：这里是我的日志看起来像..。

2014-07-13 03:08:28.684 PostTestApp[77268:6675567] Adding event to array to be sent: 1
2014-07-13 03:08:28.684 PostTestApp[77268:6675567] Adding event to array to be sent: 2
2014-07-13 03:08:28.684 PostTestApp[77268:6675567] Adding event to array to be sent: 3
2014-07-13 03:08:28.684 PostTestApp[77268:6675567] Adding event to array to be sent: 4
2014-07-13 03:08:28.684 PostTestApp[77268:6675567] Adding event to array to be sent: 5
2014-07-13 03:08:28.684 PostTestApp[77268:6675567] Adding event to array to be sent: 6
2014-07-13 03:08:29.191 PostTestApp[77268:6675567] JSON: {
    description = "Server response from /events";
    name = response;
}
2014-07-13 03:08:29.192 PostTestApp[77268:6675567] Removing event at index: 1
2014-07-13 03:08:29.192 PostTestApp[77268:6675567] Removed event from row: 1
2014-07-13 03:08:29.195 PostTestApp[77268:6675567] Removing event at index: 3
2014-07-13 03:08:29.195 PostTestApp[77268:6675567] Removed event from row: 3
2014-07-13 03:08:29.196 PostTestApp[77268:6675567] Removing event at index: 5
2014-07-13 03:08:29.197 PostTestApp[77268:6675567] Removed event from row: 5

• "Adding event to array to be sent:"是一个for循环，它将数据库is添加到arrayOfIds中。
• "Removing event at index:"发生在inDatabase:块中。
• "Removed event from row:"发生在removeWithId:内部。

编辑2:

没有编辑的完整代码块：https://gist.github.com/jonalmeida/27bee72b9015d45434e8

Answer 1

根据您的要点，您的实际代码如下所示：

for (int i=0; i < dbIndexArray.count; i++) {
    NSLog(@"Removing event at index: %@", dbIndexArray[i]);
    [_db removeEventWithId:[[dbIndexArray objectAtIndex:i] longLongValue]];
    [dbIndexArray removeObjectAtIndex:i];
}

问题是:在迭代数组时，您正在修改它。当您删除对象0，而对象1变成对象0时。

试试这个：

NSMutableArray *removedIDs = [NSMutableArray array];

for (int i=0; i < dbIndexArray.count; i++) {
    NSLog(@"Removing event at index: %@", dbIndexArray[i]);
    [_db removeEventWithId:[[dbIndexArray objectAtIndex:i] longLongValue]];
    [removedIDs addObject:dbIndexArray[i];
}

[dbIndexArray removeObjectsInArray:removedIDs];