Question

Situation: In the main View Controller, I have a UIScrollView and within that I have a UIView all working fine (View Controller > UIScrollView > UIView).

//In the main view controller...
- (void)viewDidLoad {
     UIView *subview1 = [[UIView alloc] initWithFrame:rect1]; //create a UIView
     [self.scrollView addSubview:subview1]; //add it to UIScrollView
}

Question: How can I pass a string from that UIView back to my Main View Controller?

Answer 1

Common solution is delegation. You create a custom UIView subclass that knows how to report the information to whoever is interested:

@interface MyView : UIView {}
@property(assign) id delegate;
@end

@implementation MyView

- (void) somethingHappened
{
    [delegate stringDidChange:newStringValue];
}

@end

@implementation MyController

- (void) viewDidLoad
{
    MyView *subview = …;
    [subview setDelegate:self];
}

- (void) stringDidChange: (NSString*) newStringValue
{
    NSLog(@"New string value reported from the view: %@.", newStringValue);
}

@end

If you want to, you can create a protocol for the delegate, so that the compiler can check more things for you. Note that the delegate is an assigned property, not retained, because retained property would lead to a retain cycle.

The problem can also be solved using notifications, KVO or blocks.