CODEWITHSUNDEEP
iosobjective-c
Smit Saraiya
Smit Saraiya

Reputation: 391

how To set and pass value of variable which also accesible in another View objective C

In AppDelegate.h

@property(strong,nonatomic)NSString *str2;

In ViewController.m

AppDelegate *c3=[[AppDelegate alloc]init];
c3.str2= @"Hello";

NSLog(@"Output:-%@",c3.str2);

Output:-Hello

Navigation code in Tableview didselect method(view Controller):-

Class2  *c2=[self.storyboard instantiateViewControllerWithIdentifier:@"cl2"];
[self.navigationController pushViewController:c2 animated:YES];

In Class2.m:-

AppDelegate *c3=[[AppDelegate alloc]init];
NSLog(@"%@",c3.str2);

Output:-Null

Upvotes: 0

Views: 71

Answers (2)

Rafał Sroka
Rafał Sroka

Reputation: 40038

In AppDelegate.h

@property(strong,nonatomic) NSString *str2;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    _str2 = "Hello"
}

In ViewController.m and any other view controller that wants to access str2:

AppDelegate *delegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
NSLog(@"Output: %@", delegate.str2);

Never create AppDelegate object on your own. Instead, access its instance via sharedApplication.

Upvotes: 2

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 727047

First, let's fix your current approach: the reason some recommend using app delegate to store shared values is that there is one easily accessible instance of it. You never create a new app delegate, but access the shared one instead:

AppDelegate *c3 = (AppDelegate*)[[UIApplication sharedApplication] delegate];

Once you replace [[AppDelegate alloc]init] with the above, your code will start working the way you expect.

However, this solution is not ideal. App delegate is not supposed to be a place for storing shared values; they should be stored in your model object (as "M" in MVC, Model-View-Controller). Create a singleton model object, place shared variable in it, and use that shared variable by accessing the singleton from different view controllers.

Upvotes: 5

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