SKYDatabase *publicDB = [[SKYContainer defaultContainer] publicCloudDatabase];
[publicDB saveRecord:todo completion:^(SKYRecord *record, NSError *error) {
    if (error) {
        // Here you have an error object, which means the saving operation is failed.
        // you can get an error message by this:
        NSString *errorString = error.userInfo[SKYErrorMessageKey];
        // The above error message is returned from skygear server, and is intended for developer.

        // If you need a string to display to user, you can use `-[NSError localizedDescription]`
        NSString *errorString = [error localizedDescription];
        // For example: "You are not allowed to perform this operation."


        // You can handle the error even better by providing custom error message based on the context, and error code.
        if ([error code] == SKYErrorAccessTokenNotAccepted) {
            UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Error occurred"
                                                                           message:@"You are logged out remotely"
                                                                    preferredStyle:UIAlertControllerStyleAlert];
            [alert addAction:[UIAlertAction actionWithTitle:@"OK"
                                                      style:UIAlertActionStyleDefault
                                                    handler:nil]];
            [self presentViewController:alert
                               animated:YES
                             completion:nil];
        }
        return;
    }
}];

let publicDB = SKYContainer.defaultContainer().publicCloudDatabase
publicDB.saveRecord(record) { (record : SKYRecord!, error : NSError!) in
    if let error = error {
        // Here you have an error object, which means the saving operation is failed.
        // You can get an error message by this:
        let userFriendlyString = error.userInfo[SKYErrorMessageKey] as! String
        // The above error message is returned from skygear server, and is intended for developer.

        // If you need a string to display to user, you can use `-[NSError localizedDescription]`
        let errorMessage = error.localizedDescription
        // For example: "You are not allowed to perform this operation."

        // You can handle the error even better by providing custom error message based on the context and error code.
        if SKYErrorCode(error.code) == SKYErrorAccessTokenNotAccepted {
            let alert = UIAlertController(title: "Error",
                                          message: "You are logged out remotely",
                                          preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "OK",
                                          style: UIAlertActionStyle.Default,
                                          handler: nil))
            self.presentViewController(alert,
                                       animated: true,
                                       completion: nil)
        }
    }
}