Global Variable problem

Question

I define a global variable flag in global.h file,when i click next tab bar then i can not access the flag value.I want a global variable for all tabs.please suggest me.

Answer 1

Did you include this file into place where you want to use this flag?

Answer 2

If you want a global variable, here are some options you can try:

1) Define static variables in global.h. E.g. you want to have a NSString global variable, declare the following in global.h:

@interface global : NSObject {

}
+(NSString*)MY_STR;

@end

Then implement it as static in global.m:

static NSString* MY_STR;

@implementation global

+(void) initialize
{

MY_STR = @"global string";      

}

+(NSString*)MY_STR{
    return MY_STR;
}

Then in any class that needs this variable, you can import global.h and access it as below:

[global MY_STR];

2) In this approach, define a singleton class and use its properties. You can create global as a singleton class. Declare a static getInstance method in global.h:

@interface global : NSObject{
  NSString *MY_STR;
}
@property(nonatomic, retain) NSString *MY_STR;
+(global*)getInstance;
@end

In global.m, declare a static sharedInstance:

@implementation global

@synthesize MY_STR;

static global *g;

+(global*)getInstance{
    @synchronized([global class]){
        if(g == nil){
            g = [[global alloc] init];
        }
    }
    return g;   
}

@end

In any class that needs to access MY_STR, import global.h and write the following:

global *g1= [global getInstance];
g1.MY_STR;

3) The third approach would be to declare variables in app delegate and access them.

Answer 3

Use Getter and Setter Method for each Tab's click event.

Answer 4

for a (not-objective) c approach:

in global.h

extern int flag;

in global.m

int flat;

in any other .m or .c

#import "global.h"

flag = 123; // set
int abc = flag; // get