Getting error when calling method in AppDelegate from a button action. - ios

Question

When I click "save" I am getting an error when it talks back to the AppDelegate.
I'm sure, that I'm missing something small here, but if anyone has a quick answer it would be greatly appreciated.
Here's the error I'm getting:
-[AppDelegate saveNewUsername:username:]: unrecognized selector sent to instance 0x8e403d0
Here's my button action:
-(IBAction)saveButtonPressed:(id)sender
{
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSString *userid = [appDelegate retrieveFromUserDefaults:#"userid"];
NSMutableArray *currentUser = [appDelegate getUserInfo:userid];
NSString *currentUsername = [currentUser objectAtIndex:0];
NSLog(#"%#", userid);
if ([currUsername.text isEqualToString:currentUsername]) {
//here we'll check and make sure the new username is valid and doesn't already exist (for now just update local DB)
if ([theNewUsername.text isEqualToString:#""]) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"" message:#"You must enter something for your new username." delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil, nil];
[alert show];
} else {
int returnVal = [appDelegate saveNewUsername:userid username:theNewUsername.text];
if (returnVal == 1) {
[self dismissModalViewControllerAnimated:YES];
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"There was an error saving to the database." delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil, nil];
[alert show];
}
}
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"" message:#"The username you entered is not your current username." delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil, nil];
[alert show];
}
}
And here's my AppDelegate method:
-(int)saveNewUsername:(NSString *)user_id username:(NSString *)username
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:#"somedbname.sqlite3"];
FMDatabase *db = [FMDatabase databaseWithPath:writableDBPath];
if (![db open]) {
NSLog(#"Could not open db.");
return 0;
} else {
[db intForQuery:#"UPDATE user SET username=? WHERE user_id=?", username, user_id];
if ([db hadError]) {
NSLog(#"Error %d: %#", [db lastErrorCode], [db lastErrorMessage]);
return 0;
} else {
return 1;
}
}
}

Answer 1

Your code looks OK. So I guess appDelegate is actually not an instance of AppDelegate.
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
Set a breakpoint there and have a look in the debugger to check whether it is indeed an instance of AppDelegate.