global variable read/write access


I need to access (read/write) some variables in all of my views.

The variables will be defined in view 1, then used and set to a new value in view 2.

How can i do this?


Ya , there is much a easy way to handle this.....

You can take a Global Variable

In your Delegate.h file declare your variable:

@interface Smoke_ApplicationAppDelegate : NSObject { UIWindow *window; UINavigationController *navigationController; NSString *messageString; //This would be your String Variable } @property(nonatomic,retain)NSString *messageString;

Secondly in Delegate.m file

@implementation Smoke_ApplicationAppDelegate @synthesize window; @synthesize navigationController; @synthesize messageString; //

Synthesize it over here..

This is Done .Now you can use this String Variable in All/any class you want..

To use this Global Variable.

Just import you Delegate file make the obj of it....

import "DelegateFile.h" @implementation About DelegateFile *appDel;

Now in Your class.m

-(void)viewDidLoad { [super viewDidLoad]; appDel=[[UIApplication sharedApplication]delegate]; }

Now you can access it anywhere in your class by this Object:


Just follow my Steps Carefully After giving so much pain to my finger, I am sure this is definitely going to help you.....

Have a easy life,


Please don't declare them as instance variables on your application delegate, it's not really good design practice for MVC.

Your best option is to create a shared data model. This can be what is called a 'singleton' class so there is only every 1 instance of it. This model class can then store any central information that is needed by various views.

Rob Napier's answer <a href="https://stackoverflow.com/questions/2410830/apple-singleton-example-query" rel="nofollow">over here</a> is a good reference as are other links from that page. In particular I'd commend <a href="http://www.mikeash.com/pyblog/friday-qa-2009-10-02-care-and-feeding-of-singletons.html" rel="nofollow">Mike Ash's post here</a>.

'Singletons' are great. They encapsulate the data in a model class where it belongs and avoid creeping global variables which make code less easy to decouple in future.


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