How to change the Application Delegate class?

Question

In every iOS app there is an App Delegate class, meaning one of the classes in the app has to implement the delegate methods for the application events such as didFinishLaunching: and so forth. Usually the class name contains "AppDelegate".

The App Delegate class is a subclass of UIApplicationDelegate on iOS or NSApplicationDelegate on the Mac.

class AppDelegate: UIApplicationDelegate {

}

Let's say I want to implement the App Delegate methods in a different class than the original one Xcode created and named for me. How can I do that?

Answer 1

You can do the same by modifying the parameters to the UIApplicationMain function present in the main.m file:

UIApplicationMain(argc,argv,nil,nil);

The last parameter takes the name of the class which is implementing the UIApplicationDelegate protocol.

So the default implementation looks something like:

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, nil, nil);
[pool release];
return retVal;

After modifying it will be something like:

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, nil, NSStringFromClass([< Your class name will go here > class]));
[pool release];
return retVal;

Answer 2

I achieved this in Swift by changing the AppDelegate's default template implementation:

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

replace with:

import UIKit

@UIApplicationMain
class MyAppAppDelegate: UIResponder, UIApplicationDelegate {

See the new class name.