NSUserDefaults errors in logs

Question

I get some error messages in logs

[User Defaults] Failed to write value for key GameId in CFPrefsPlistSource<0x1740faf00> (Domain: xxx.xxxxxx, User

Answer 1

I'd like to share my solution for this problem. For my case, the error was a legitimate error and my data was not saved properly. It turns out the error was caused by having a NSUserDefaults "data saving" in a loop.

By "data saving" I mean this (pseudocode):

loop{
    [defaults setObject:@"Data" forKey:@"Key"];
    [defaults synchronize];
}

So the code executes this multiple times very fast and cause the problem. I guess "synchronize" cannot handle concurrent calls.

What needs to be done is:

loop{
    [defaults setObject:@"Data" forKey:@"Key"];
}
[defaults synchronize];

synchronize be called once after all the objects been set.