Delegate function not called in AppDelegate

Question

I have written protocol in a view controller, and implement it in AppDelegate, and when I call delegate function from view controller, the delegate function is not called. Below is my code -

In class AuthenticationViewController -

@class AuthenticationViewController;
@protocol ApplicationTiomeoutDelegate <NSObject>

-(void) addObserverForTimeout;

@end

And call this function using delegate -

[self.appTimeoutDelegate addObserverForApplicationTimeout];

And in AppDelegate, I have implemented this protocol like this -

@interface AppDelegate () <ApplicationTiomeoutDelegate>
@end

And then set delegate to self -

AuthenticationViewController *timeoutDelegate = [[AuthenticationViewController alloc] init];
[timeoutDelegate setAppTimeoutDelegate:self]; 

And implemented delegate function as well in AppDelegate, which is never called somehow -

-(void) addObserverForApplicationTimeout{
 // this function is never called 
} 

I am not sure what is not correct here.

Answer 1

AppDelegate being a singleton need not have the ApplicationTiomeoutDelegate protocol invocation. You can directly invoke addObserverForTimeout

Answer 2

You create method in your appdelegate , you can directly call it wherever you want with instance of appdelegate .

For your question, check this below

Where are creating instance for Your delegate and where are calling your delegate form your viewcontroller , it is used to communicate between two class, it should have reference of protocol.

try this

Your viewcontroller.h

@protocol customDelegate;
#import <UIKit/UIKit.h>
#import "CustomTableViewCell.h"

@interface ViewController : UIViewController<UITableViewDelegate>
{

    IBOutlet UITableView *mainTableView;
}
@property (nonatomic,strong) id <customDelegate> delegate;
@end

@protocol customDelegate <NSObject>

-(void)method;

@end

ViewController.m

- (void)viewDidLoad {
    [self.delegate method];
}

Your app delegate

@interface AppDelegate () <customDelegate>
@end

Your didfinishlaunghing

viewController = [[ViewController alloc]initWithNibName:@"ViewController" bundle:nil];
    viewController.delegate = self;

and implement method:

-(void)method{
    NSLog(@"calling");
}