Declaring CustomViewController?

Question

I have noticed in some of my older apps that in situations where I have added a custom View Controller I have not changed the View Controller class in the application delegate. For example, below I have created a CustomViewController class but have declared viewController as UIViewController.

@interface ApplicationAppDelegate: NSObject <UIApplicationDelegate> {
    UIWindow *window;
    UIViewController *viewController;
}

My question is, both work, but for correctness should I be writing this as follows:

@class CustomViewController;
@interface ApplicationAppDelegate: NSObject <UIApplicationDelegate> {
    UIWindow *window;
    CustomViewController *viewController;
}

gary

Answer 1

Yes, you should retrofit your existing member type definitions to be as specific as possible.

In the header file, you should always forward declare your instance objects.

This saves you from actually importing the class header, thereby saving a little overhead.

Forward declare as much as you can in header files, then #import in your implementation files.

Here's an example:

Header file:

@class CustomViewController;
@interface ApplicationAppDelegate: NSObject <UIApplicationDelegate> {
    UIWindow *window;
    CustomViewController *viewController;
}

---

Implementation file:

#import "CustomViewController.h";

@implementation ApplicationAppDelegate

...

@end