Question

I have an object declared in my app delegate:

@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
    ClassName *className;
}

In another class, I include the app delegate:

#import "MyAppDelegate.h"

@implementation AnotherClass
-(void)doMethod {
    [className doClassNameMethod];
}

This fails at compile time due to className being undeclared. Shouldn’t it be accessible, since I’ve included the MyAppDelegate, where className is declared? I need AnotherClass.doMethod to be accessing the same instance that is created in MyAppDelegate.

Any help on this would be most appreciated. Thanks.

Answer 1

To access a instance variable in one class from another class, you should create a property.

@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
    ClassName *className;
}

@property (nonatomic, readonly) ClassName *className;

...
@end

From the other class you may then access this property like this:

@implementation AnotherClass
- (void) doMethod {
    MyAppDelegate *delegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
    [delegate.className doClassNameMethod];
}
@end