AppDelegate is a traditional example of bad code. Lots of line of code that makes so much different things are put together in methods that are called within the application life cycle. But all of those concerns are over. Using PlugAppDelegate you decouple AppDelegate from the services that you plug to it. Each ApplicationService has its own life cycle that is shared with AppDelegate.

Let see some code. Here is how a ApplicationService is like:

#import "LoggerApplicationService.h"

@implementation LoggerApplicationService

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
     NSLog(@"LoggerApplicationService didFinishLaunchingWithOptions");
    return YES;
}

@end

That's all. It is exactly the same as a AppDelegate. Think of ApplicationService as sub-AppDelegates.

In AppDelegate you just have to inherit from PluggableApplicationDelegate to register the services.

#import "AppDelegate.h"
#import "LoggerApplicationService.h"
#import "PushApplicationService.h"

@interface AppDelegate ()

@end

@implementation AppDelegate


- (NSArray<ApplicationService> *)services {
    if (![super services]) {
        super.services = (NSArray<ApplicationService>*)@[[LoggerApplicationService new],
                                                         [PushApplicationService new]];
    }
    return super.services;
}


@end

Basically, you do an inversion of control. Instead of let AppDelegate instantiate your dependencies, perform actions at every step of its life cycle, you create objects that share the AppDelegate life cycle and plug them into your AppDelegate. Those objects are observers of the AppDelegate. Your AppDelegate has the only responsibility of notify them about its life cycle events.

To run the example project, clone the repo, and run pod install from the Example directory first.

PluggableApplicationDelegate is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "PlugAppDelegate"

Obj-C version: Sergey Makkena [email protected]

Swift version: fmo91, [email protected] PluggableApplicationDelegate

PlugAppDelegate is available under the MIT license. See the LICENSE file for more info.