Question

I have a UIViewController with a UIView as a subview. I’d like the UIViewController to be notified of (or listen for) certain actions in the UIView. What’s the standard way of doing this?

Answer 1

If you just want to have an action handler:

- (void)viewDidLoad {
    [super viewDidLoad];
    // ......
    UIButton *myButton = [[UIButton alloc] init]; // or initWithSOMETHING
    [myButton addTarget:self action:@selector(someMethod:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:myButton];
    [myButton release];
    // ......
}

- (void)someMethod:(id)sender {
    if (![sender isKindOfClass:[UIButton class]]) return;
    // Do something about the action here...
}

For more info, see the UIControl Documentation:

Preparing and Sending Action Messages

– sendAction:to:forEvent:
– sendActionsForControlEvents:
– addTarget:action:forControlEvents:
– removeTarget:action:forControlEvents:
– actionsForTarget:forControlEvent:
– allTargets
– allControlEvents

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Or, if your talking about a view controller calling a parent view controller, you could use the presentingViewController property of a UIViewController to access the “parent” view controller:

UIViewController *parentVC = [self presentingViewController];
[parentVC setSomething:self.withSomething];

presentingViewController – The view controller that presented this view controller. (read-only)

@property(nonatomic, readonly) UIViewController
*presentingViewController

Discussion
The default implementation of this property walks up the view
hierarchy, starting from this view controller. The first view
controller it finds that received the
presentViewController:animated:completion: method, or that has its
definesPresentationContext property set to YES is returned as the
value of the property. It keeps walking up the hierarchy until it
finds a value to return or it gets to the root view controller.

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Or the superview property of a UIView:

[self.view.superview doSomething];

superview – The receiver’s superview, or nil if it has none. (read-only)
@property(nonatomic, readonly) UIView *superview