ModuleAdapter.md

Module Adapter

If you don't want to depend same protocol in module and module's user, use adapter to make totally decouple.

Provided protocol and Required protocol

A router can register with multi protocols. The protocol provided by module itself is the provided protocol. The protocol used inside the module's user is the required protocol。

See Required Interface and Provided Interface in component diagramscomponent diagrams:

Read VIPER architecture to get more details about implementing Required Interface and Provided Interface.

App Context is responsible for adapting interfaces. The module's user uses Required Interface, and the adapter forwards Required Interface to Provided Interface.

Add Required Interface for module

Add required protocol for module with category and extension in app context.

For example, a module A needs to show a login view, and the login view can display a custom tip.

Module A:

protocol ModuleARequiredLoginViewInput {
  var message: String? { get set } //Message displayed on login view
}
//Show login view in module A
Router.perform(
    to RoutableView<ModuleARequiredLoginViewInput>(),
    path: .presentModally(from: self)
    configuring { (config, _) in
        config.prepareDestination = { destination in
            destination.message = "Please login to read this note"
        }
    })

Objective-C Sample

@protocol ModuleARequiredLoginViewInput <ZIKViewRoutable>
@property (nonatomic, copy) NSString *message;
@end

//Show login view in module A
[ZIKRouterToView(ModuleARequiredLoginViewInput)
	          performPath:ZIKViewRoutePath.presentModallyFrom(self)
	          configuring:^(ZIKViewRouteConfiguration *config) {
	              config.prepareDestination = ^(id<ModuleARequiredLoginViewInput> destination) {
	                  destination.message = @"Please login to read this note";
	              };
	          }];

ZIKViewAdapter and ZIKServiceAdapter are responsible for registering protocols for other router.

Make login view support ModuleARequiredLoginViewInput:

//Login Module Provided Interface
protocol ProvidedLoginViewInput {
   var notifyString: String? { get set }
}

//Write in app context, make ZIKEditorViewRouter supports ModuleARequiredLoginViewInput
class LoginViewAdapter: ZIKViewRouteAdapter {
    override class func registerRoutableDestination() {
        //If you can get the router, you can just register ModuleARequiredLoginViewInput to it
        ZIKEditorViewRouter.register(RoutableView<ModuleARequiredLoginViewInput>())
        //If you don't know the router, you can use adapter
        register(adapter: RoutableView<ModuleARequiredLoginViewInput>(), forAdaptee: RoutableView<ProvidedLoginViewInput>())
    }
}

extension LoginViewController: ModuleARequiredLoginViewInput {
    var message: String? {
        get {
            return notifyString
        }
        set {
            notifyString = newValue
        }
    }
}

Objective-C Sample

//Login Module Provided Interface
@protocol ProvidedLoginViewInput <NSObject>
@property (nonatomic, copy) NSString *notifyString;
@end

//LoginViewAdapter.h
@interface LoginViewAdapter : ZIKViewRouteAdapter
@end

//LoginViewAdapter.m
@implementation LoginViewAdapter

+ (void)registerRoutableDestination {
	//If you can get the router, you can just register ModuleARequiredLoginViewInput to it
	[ZIKEditorViewRouter registerViewProtocol:ZIKRoutable(ModuleARequiredLoginViewInput)];
	//If you don't know the router, you can use adapter
	[self registerDestinationAdapter:ZIKRoutable(ModuleARequiredLoginViewInput) forAdaptee:ZIKRoutable(ProvidedLoginViewInput)];
}

@end

//Make LoginViewController support ModuleARequiredLoginViewInput
@interface LoginViewController (ModuleAAdapter) <ModuleARequiredLoginViewInput>
@property (nonatomic, copy) NSString *message;
@end
@implementation LoginViewController (ModuleAAdapter)
- (void)setMessage:(NSString *)message {
	self.notifyString = message;
}
- (NSString *)message {
	return self.notifyString;
}
@end

Forward Interface with Proxy

If you can't add required protocol for module, for example, the delegate type in protocol is different:

protocol ModuleARequiredLoginViewDelegate {
    func didFinishLogin() -> Void
}
protocol ModuleARequiredLoginViewInput {
  var message: String? { get set }
  var delegate: ModuleARequiredLoginViewDelegate { get set }
}

Objective-C Sample

@protocol ModuleARequiredLoginViewDelegate <NSObject>
- (void)didFinishLogin;
@end

@protocol ModuleARequiredLoginViewInput <ZIKViewRoutable>
@property (nonatomic, copy) NSString *message;
@property (nonatomic, weak) id<ModuleARequiredLoginViewDelegate> delegate;
@end

Delegate is different in provided module:

protocol ProvidedLoginViewDelegate {
    func didLogin() -> Void
}
protocol ProvidedLoginViewInput {
  var notifyString: String? { get set }
  var delegate: ProvidedLoginViewDelegate { get set }
}

Objective-C Sample

@protocol ProvidedLoginViewDelegate <NSObject>
- (void)didLogin;
@end

@protocol ProvidedLoginViewInput <NSObject>
@property (nonatomic, copy) NSString *notifyString;
@property (nonatomic, weak) id<ProvidedLoginViewDelegate> delegate;
@end

In this situation, you can create a new router to forward the real router, and return a proxy for the real destination:

class ModuleAReqiredEditorViewRouter: ZIKViewRouter {
   override class func registerRoutableDestination() {
       registerView(/*proxy class*/)
       register(RoutableView<ModuleARequiredLoginViewInput>())
   }
   override func destination(with configuration: ZIKViewRouteConfiguration) -> ModuleARequiredLoginViewInput? {
       //Get real destination with ProvidedLoginViewInput's router
       let realDestination: ProvidedLoginViewInput = ZIKEditorViewRouter.makeDestination()
       //Proxy is responsible for forwarding ModuleARequiredLoginViewInput to ProvidedLoginViewInput
       let proxy: ModuleARequiredLoginViewInput = ProxyForDestination(realDestination)
       return proxy
   }
}

Objective-C Sample

@implementation ZIKModuleARequiredEditorViewRouter
+ (void)registerRoutableDestination {
	//Register ModuleARequiredLoginViewInput with ZIKModuleARequiredEditorViewRouter
	[self registerView:/* proxy class*/];
	[self registerViewProtocol:ZIKRoutable(NoteListRequiredNoteEditorProtocol)];
}
- (id)destinationWithConfiguration:(ZIKViewRouteConfiguration *)configuration {
   //Get real destination with ProvidedLoginViewDelegate's router
   id<ProvidedLoginViewInput> realDestination = [ZIKEditorViewRouter makeDestination];
    //Proxy is responsible for forwarding ModuleARequiredLoginViewInput to ProvidedLoginViewInput
    id<ModuleARequiredLoginViewInput> proxy = ProxyForDestination(realDestination);
    return proxy;
}
@end

For simple objc classes, you can use NSProxy to create a proxy. For those complex classes such as UIViewController in UIKit, you can subclass the UIViewController, and override methods to adapt interface.

You don't have to always separate requiredProtocol and providedProtocol. It's ok to use the same protocol in module and its user. Change it only when you need it.