我在Xcode控制台中看到以下错误，但我不知道它所抱怨的只读数据库是什么：
CPSqliteStatementPerform: attempt to write a readonly database for UPDATE ddd.ext_container SET orig_date_modified = (SELECT date_modified FROM container WHERE pid=container_pid) WHERE orig_date_modified=0
CPSqliteStatementReset: attempt to write a readonly database for UPDATE ddd.ext_container SET orig_date_modified = (SELECT date_modified FROM container WHERE pid=container_pid) WHERE orig_date_modified=0
以下代码在错误之前执行：
MPMediaQuery *myPlaylistsQuery = [MPMediaQuery playlistsQuery];
NSArray *array = [myPlaylistsQuery collections];
playlists = [[NSMutableArray alloc] init];
[playlists addObject:@"new playlist"];
NSLog(@"%@", [playlists objectAtIndex:0]);
int numPlaylists = 1;
for (MPMediaPlaylist *arrayItem in array) {
NSLog(@"Got here");
NSLog打印出'new playlist'
然后在for循环初始化之后，CPSqliteStatementPerform:和CPSqliteStatementReset:错误立即打印出来。
然后NSLog打印出'Got here'。
我正在写哪个只读数据库，如何纠正这个问题？