How can I specify a target for my action to point to?

Question

I'm learning objective-c for iOS and have a question about creating my first target-action mechanism. I've got it to work, but currently I just set the target: portion of the addTarget:action:changeForControlEvents: method to nil, meaning it will search around my app for the target instead of drilling down on ViewController.m, where the method I want to send a message is located.

How can I tell the addTarget:action:changeForControlEvents: method which class to search first?

Here is a simple version of my current code:

The view:

// View.m
#import View.h

@implementation

- (void)sendAction
{
     UIControl *button = [[UIControl alloc] init];
     [button addTarget:nil  // How do I make this look for ViewController.m?
                action:@selector(changeButtonColor) 
changeforControlEvents:UIControlEventTouchUpInside];
}
@end

...and the View Controller:

// ViewController.m
#import ViewController.h

@implementation

- (void)target
{
     NSLog(@"Action received!");
}
@end

Thanks for the help!

Answer 1

You cannot simply called UIViewController if it doesn't load or allocate in the memory. To achieve this you need to alloc that class.

one way to do using singleton

[button addTarget:[ViewController sharedManager] action:@selector(target) 
forControlEvents:UIControlEventTouchUpInside];

or using NSNotificationCenter, assuming that the class is already running (stack in previous navigation / another tabs).

// View.m
#import View.h
@implementation

- (void)sendAction
{
     UIControl *button = [[UIControl alloc] init];
     [button addTarget:self 
                action:@selector(controlAction) 
changeforControlEvents:UIControlEventTouchUpInside];
}

-(void)controlAction
{
 [[NSNotificationCenter defaultCenter] 
        postNotificationName:@"changeButtonColor" 
        object:self];
}
@end

and for target UIViewController

// ViewController.m
#import ViewController.h

@implementation
-(void) viewDidLoad
{
   [[NSNotificationCenter defaultCenter] addObserver:self
        selector:@selector(receiveNotification:) 
        name:@"changeButtonColor"
        object:nil];

- (void)receiveNotification:(NSNotification *) notification

{
     NSLog(@"Action received!");
}
@end

Answer 2

Assuming ViewController is the VC that created the view you're working in you should be able to use:

addTarget:[self superview]