Error in Objective treated as Object and inherited NSObject.

NSError object encapsulate three types of information

1) Code - Nsinteger value which give the errors unique identifier

2) Domain - NSString value having error domain

3) userInfo - NSdictionary instance that have application specific information related to that error

Following is the list of the standard NSError userInfo keys:

1. NSLocalizedDescriptionKey
2. NSLocalizedFailureReasonErrorKey
3. NSLocalizedRecoverySuggestionErrorKey
4. NSLocalizedRecoveryOptionsErrorKey
5. NSFilePathErrorKey
6. NSStringEncodingErrorKey
7. NSUnderlyingErrorKey
8. NSRecoveryAttempterErrorKey
9. NSHelpAnchorErrorKey

Here is the Usage of NSError

NSError *error = nil;
BOOL success = [[NSFileManager defaultManager] moveItemAtPath:@"path"
                                                       toPath:@"destinationpath"
                                                        error:&error];
if (!success) {
    NSLog(@"%@", error);
}