Octal escape sequence out of range
NSURLCredential *credential = [NSURLCredential credentialWithUser:@"asdfg123456"
                                                             password:@"Zxcvb123!" persistence:NSURLCredentialPersistenceForSession];

NSURLCredential *credential = [NSURLCredential credentialWithUser:@"asdfg\123456"
                                                             password:@"Zxcvb123!" persistence:NSURLCredentialPersistenceForSession];

NSURLCredential *credential = [NSURLCredential credentialWithUser:@"asdfg\123456"
                                               password:@"Zxcvb123!"
                                               persistence:NSURLCredentialPersistenceForSession] ;