Question

I have a NavigationController that present a view (ShoppingController) with a button which one I call a ModalViewController :

    AddProductController *maView = [[AddProductController alloc] init];
maView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:maView animated:YES];

When I want exchange data from my modal view to his parent, I have an error because [self parentViewController] refer to my NavigationController and not my ShoppingController.

How can I send data from my ModalView AddProductController to my caller ShoppingController ?

Answer 1

You could use the delegate pattern.

In your AddProductController class, when handling the button tap, you can then send a message to its delegate, which you set as your ShoppingController.

So, in AddProductController:

-(void)buttonHandler:(id)sender {
    // after doing some stuff and handling the button tap, i check to see if i have a delegate.
    // if i have a delegate, then check if it responds to a particular selector, and if so, call the selector and send some data
    // the "someData" object is the data you want to pass to the caller/delegate
    if (self.delegate && [self.delegate respondsToSelector:@selector(receiveData:)])
        [self.delegate performSelector:@selector(receiveData:) withObject:someData];
}

Then, in ShoppingController (and don’t forget to release maView):

-(void)someMethod {
    AddProductController *maView = [[AddProductController alloc] init];
    maView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    maView.delegate = self;
    [self presentModalViewController:maView animated:YES];
    [maView release];
}

-(void)receiveData:(id)someData {
     // do something with someData passed from AddProductController
}

If you want to get fancy, you can make receiveData: part of a protocol. Then, your ShoppingController can implement the protocol, and instead of checking with [self.delegate respondsToSelector:@selector(x)], you check that [self.delegate conformsToProtocol:@protocol(y)].