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上一篇文章我们设计好了View和Interactor，现在我们来做Presenter。
Presenter在这个用例里面的主要作用就是接受View提交过来的“提问”请求，然后向Interactor获取“答案”，最后把结果更新到View上，以下是实现部分的代码片段：
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| @interface HumanComputerCommunicatePresenter : NSObject <AIRobotInteractorDelegate>
@property (nonatomic, weak) id<ProgressViewInterface> progressView;
@property (nonatomic, weak) id<MessageBoardViewInterface> messageBoard;
@property (nonatomic, strong) AIRobotInteractor *aiRobotInteractor;
- (void)wantSendMessage:(NSString *)message;
@end
@implementation HumanComputerCommunicatePresenter
- (void)wantSendMessage:(NSString *)message {
[self.progressView beginProgress];
[self.aiRobotInteractor askQuestion:message]
}
- (void)aiRobotInteractor:(AIRobotInteractor *)aiRobotInteractor didResponseToQuestion:(NSString *)question response:(NSString *)response {
[self.progressView endProgress];
[self.messageBoard showMessage:response];
}
@end
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可以发现，Presenter就是承担了一个中间者的角色，它才是传统意义上MVC机构中的C(Controller)。其中有一点要注意的是，对应ViewInterface的reference，我们采用了weak的定义来防止Strong reference cycle ，在我自己的设计当中，我偏向于如下的reference关系：
- View —strong-> Presenter
- Presenter —strong-> Interactor
- Presenter —weak-> View
最后我们来看一下Routing，objc.io那片文章中的Routing做的很散，通过多个wireframe来实现，我个人的设计中偏向用一个大的wireframe结合Assembling Factory来实现Routing，废话不多说看代码比较直观，以下只是我个人目前的一种实现方案，仅供参考：
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| @implementation AssemblingFactory
+ (UIViewController *)assembleChatroomView {
ChatroomViewController *viewController = [[UIStoryboard genericStoryboard] instantiateViewControllerWithIdentifier:ChatroomViewIdentifier];
HumanComputerCommunicatePresenter *presenter = [HumanComputerCommunicatePresenter new];
AIRobotInteractor *interactor = [AIRobotInteractor new];
viewController.presenter = presenter;
presenter.progressView = viewController;
presneter.messageBoard = viewController
presenter.interactor = interactor;
interactor.delegate = presenter;
return viewController;
}
@end
@implementation Wireframe
+ (void)moveToNextPageOfViewController:(UIViewController *)viewController messenger:(PageMessenger *)messenger {
SEL selector = [self selectorOfClass:[viewController class] messengerName:[messenger name]];
IMP imp = [[self class] methodForSelector:selector];
void (*func)(id, SEL, UIViewController*, NSDictionary*) = (void *)imp;
func([self class], selector, viewController, [messenger params]);
}
+ (SEL)selectorOfClass:(Class)class messengerName:(NSString *)messengerName {
static NSDictionary *selectorMap = nil;
if (!selectorMap) {
selectorMap = @{
@"SplashViewControllerDefault" : [NSValue valueWithPointer:@selector(moveToChatroomViewController:params:)]
// add more nav configuration here...
};
}
NSValue *value = [selectorMap valueForKey:[[class description] conj:messengerName]];
return value ? [value pointerValue] : @selector(emptyMove:params:);
}
+ (void)moveToChatroomViewController:(UIViewController *)viewController params:(NSDictionary *)params {
UIViewController *viewController = [AssemblingFactory assembleChatroomView];
[(BaseViewController *)viewController setParams:params]; // I defined a base view controller to allow pass params
[viewController.navigationController pushViewController:viewController animated:YES];
}
@end
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以上大致就是我个人目前实践VIPER的一些心得，肯定非常不成熟，有很多地方可以改进，只想抛砖引玉让大家广思集益共同改进我们代码的架构方案，从而最终帮助提高开发效率。
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