How to access a variable's value from one class, if the variable is defined in another? (Objective-C)

Question

I have two pairs (.m and .h) of files. In one's interface section, I've defined a global BOOL variable. I need to get it's value in another class. How can I do it? (I can't make one class a subclass of another).

In one file I have

@interface TabBarRotation : UITabBarController {
    BOOL portrait;
}

@end



@implementation TabBarRotation

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return YES;
}

- (void):(UIInterfaceOrientation) interfaceOrientation  { 
if (interfaceOrientation == UIInterfaceOrientationPortrait||interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown) {
    portrait=YES;
} 
else if (interfaceOrientation == UIInterfaceOrientationLandscapeLeft || interfaceOrientation == UIInterfaceOrientationLandscapeRight) {
    portrait=NO;
} 
}

@end

And in another's @implementation I have

- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {
if(portrait==YES) {
    CalcPortraitViewController *CalcPortraitController;
    CalcPortraitController = [[CalcPortraitViewController alloc] 
                 initWithNibName:@"CalcPortraitView" bundle:nil];
    CalcPortraitController.title=@"Калькулятор";
    CalcPortraitController.hidesBottomBarWhenPushed=YES;    
    [self.navigationController pushViewController:CalcPortraitController
                                     animated:NO];  
    [self.navigationController setNavigationBarHidden:YES animated:NO];
}
else if (portrait==NO) {
    CalcLandscapeViewController *CalcLandscapeController;
    CalcLandscapeController = [[CalcLandscapeViewController alloc] 
                              initWithNibName:@"CalcLandscapeView" bundle:nil];
    CalcLandscapeController.title=@"Калькулятор";
    CalcLandscapeController.hidesBottomBarWhenPushed=YES;    
    [self.navigationController pushViewController:CalcLandscapeController
                                         animated:NO];  
    [self.navigationController setNavigationBarHidden:YES animated:NO];
}

}

Answer 1

If you really want a global variable, you don't want it to be in the interface of either class. You can access global variables just like you would in C. Use:

extern BOOL myGlobal;

to declare the variable anywhere you need to use it (or in a common header might be ideal). Then define it in exactly one place:

BOOL myGlobal;

And you should be set.

If you do want it to be an instance variable of a class, you can make an accessor like you normally would to get at that variable from another class.