How to use Static Variable to save a string in objective-c? - ios

Question

I want to use Static Var to save a NSString.
So I define a Static Var in a .h file like this:
#ifndef GlobalParameters_h
#define GlobalParameters_h
//access token
static NSString *applicationToken;
#endif
In class A, I change the static var like this:
#import "ClassA.h"
#import "GlobalParameters.h"
extern NSString *applicationToken;
#implementation ClassA
+ (void)parseResponse:(NSString *)response
{
NSDictionary *responseDic = [response objectFromJSONString];
NSString *token = [responseDic objectForKey:#"token"];
applicationToken = [token copy];
NSLog(#"%#",applicationToken);
}
When the debugger run to
applicationToken = [token copy];
I found the "applicationToken" is nil,but the next sentence
NSLog(#"%#",applicationToken);
can output the right value in console! And in ClassB , the "applicationToken" is nil too.
I don't know why the static var is nil. I think the compiler will find the definition of "applicationToken" in GlobalParameters.h.But why I can't modify the static value?
Thanks for your help:)

Answer 1

static global variable mean that it's own for every object-file it's used. So there is willbe own applicationToken for ClassA, ClassB.
To create global variable for all object-files you need this:
In GlobalParameters.h:
#ifndef GlobalParameters_h
#define GlobalParameters_h
//access token
extern NSString *applicationToken;
#endif
In GlobalRarameters.m:
#import "GlobalParameters.h"
NSString *applicationToken;
P.S. I hope you use ARC, because if not, then applicationToken = [token copy]; will cause memory leaks.

Answer 2

Hey Its working fine , I am checking like this
Once check the are you getting "responseDic" (or) not , Check the
The dictionary have token key
static NSString *applicationToken;
applicationToken = #"srinivas";
NSLog(#"%#",applicationToken);
NSDictionary *responseDic = [NSDictionary dictionaryWithObject:#"static" forKey:#"token"];
NSString *token = [responseDic objectForKey:#"token"];
applicationToken = [token copy];
NSLog(#"%#",applicationToken);
[AppDelegate parseResponse:responseDic];