Question

I have following code:

     LoginViewController *lvc = [[LoginViewController alloc] initWithNibName:@"LoginViewController" bundle:nil];
 [self presentModalViewController:lvc animated:false];
 [lvc release];

That is called from my MainViewController.

Now, when the LoginViewController will be dismissed (of course this only happens when the login is correct) I must call a method in my MainViewController to load the initial data for my app.

I read a lot about delegate and tried it, but don’t get it to work.
Could someone help me please?

(if possible, please with a few lines of code)
Any help is welcome!

Answer 1

I read a lot about delegate and tried it, but don’t get it to work.

What have you tried really? Your LoginViewController must define a simple delegate protocol, and your MainViewController must conform to it.

All you need to do is add something like this in LoginViewController.h above @interface:

@protocol LoginViewControllerDelegate

- (void)loginViewControllerDidFinish;

@end

Which declares a protocol with one method. Then add this between @interface and @end:

@property (nonatomic, assign) id <LoginViewControllerDelegate> delegate;

Which means your login view controller will have a property called delegate which will point to an instance of any class (that’s what id means) that conforms to it’s delegate protocol (the thing between < and >). Don’t forget to @synthesize delegate; inside .m file.

Now what you need to do is inside MainViewController.h add to @interface line like this:

@interface MainViewController : UIViewController <LoginViewControllerDelegate>

Which tells the compiler your MainViewController class conforms to this LoginViewControllerDelegate delegate protocol. Now implement the - (void)loginViewControllerDidFinish; method inside MainViewController.m and before presenting the login view controller modally set it’s delegate to self (login.delegate = self;). When you are done inside your login view controller, before you dismiss it, call the delegate method on your delegate:

[self.delegate loginViewControllerDidFinish];

And that’s it. Any more questions?