SIMPLE PROTOCOL & DELEGATE EXAMPLE

PROTOCOL & DELEGATE

two controllers

FirstViewController

SecondViewController

SecondViewController.h

@protocol SecondViewControllerDelegate;

@property (nonatomic, weak) id<SecondViewControllerDelegate> delegate;

@protocol SecondViewControllerDelegate <NSObject>

- (void)SecondViewController:(SecondViewController*)viewController

             didChooseValue:(CGFloat)value;

SecondViewController.m

-(IBAction)SecondTap:(id)sender

{

    id<SecondViewControllerDelegate> strongDelegate = self.delegate;

    

    // Our delegate method is optional, so we should

    // check that the delegate implements it

    

    if ([strongDelegate respondsToSelector:@selector(SecondViewController:didChooseValue:)]) {

        [strongDelegate SecondViewController:self didChooseValue:[sender tag]];

    }

}

FirstViewController.h

@interface FirstViewController : UIViewController<SecondViewControllerDelegate>

FirstViewController.m

-(IBAction)Add:(id)sender

{

    SecondViewController *objsecond =[[SecondViewController alloc]init];

    [objsecond setDelegate:self];

    [self.view addSubview:objsecond.view];

}

- (void)SecondViewController:(SecondViewController *)viewController didChooseValue:(CGFloat)value

{

    

    // Do something with value...

    

    // ...then dismiss the child view controller

    [viewController.view removeFromSuperview];

}