不同的方法类型?

我对objective-c中的实例和类方法很熟悉(或者至少是越来越熟悉),但也看到过类似这样的方法实现:

#import "Utilities.h"
#import "CHAPPAppDelegate.h"
#import "AppState.h"

@implementation Utilities

CHAPPAppDelegate* GetAppDelegate() {
    return (CHAPPAppDelegate *)[UIApplication sharedApplication].delegate;
}

AppState* GetAppState() {
    return [GetAppDelegate() appState];
}

@end