Question

My app is tabbar(+ navigation) application. In FirstViewController I call onModalView.

-(void) onFilter
{
  FilterViewController* controller =[[[FilterViewController alloc] initWithNibName:@"Filter" bundle:[NSBundle mainBundle]] autorelease];
  [self.navigationController presentModalViewController:controller animated:YES];
}

There are many filters that user can choose in FilterViewController. I want to transit users preferences to FirstViewController. How can I do this ?

Answer 1

I usually use a delegate pattern. Like:

@class FilterViewController;

@protocol FilterViewControllerDelegate
@required
- (void)filterViewController:(FilterViewController *)controller didSelectFilters:(NSInteger)filters;
@end

@interface FilterViewController : UIViewController {
    id<FilterViewControllerDelegate> _delegate;
}
@property (nonatomic, assign) id<FilterViewControllerDelegate> delegate;
@end

and in your FirstViewController:

-(void) onFilter
{
  FilterViewController* controller =[[[FilterViewController alloc] initWithNibName:@"Filter" bundle:[NSBundle mainBundle]] autorelease];
  controller.delegate = self;
  [self.navigationController presentModalViewController:controller animated:YES];
}

- (void)filterViewController:(FilterViewController *)controller didSelectFilters:(NSInteger)filters {
// Do something
}

In your FilterViewController call - (void)filterViewController:(FilterViewController *)controller didSelectFilters:(NSInteger)filters on the delegate before dismissing it.