Container View Controllers - notify parent of action

Question

Say I have a custom container view controller (MainViewController) where I do something like this:

- (void)viewDidLoad
{
    [super viewDidLoad];        

           


        

Answer 1

This is a very common pattern. The parent will be the actual instance that will handle the action, by providing a protocol and a default extension.

In Swift 3:

Parent view controller:

protocol SomeProtocol {
    func foo()
}

extension ParentViewController: SomeProtocol {
    func foo() {
        // Parent handles it
    }
}

Child view controller:

 @IBAction func tapGo(_ sender: Any) {
    (parent as? SomeProtocol)?.foo()
 }