Swift World：设计模式-中介者

今天我们将讨论中介者模式。 让我们从现实世界中的场景开始，而不是解释抽象定义。 在团队中，有PM，开发人员和QE。 当开发人员完成对新功能的编码后，这些代码将提交给存储库。 其他股东（如量化宽松和PM）需要通知。

protocol Collogue { 
 var id: String { get } 
 func send (message: String ) 
 func receive (message: String ) 
 } 

 class Developer : Collogue { 
 var id: String 
 var qe: QE 
 var pm: PM 

 init (qe: QE , pm: PM ) { 
 self. id = "Developer" 
 self. qe = qe 
 self. pm = pm 
 } 

 func send (message: String ) { 
 qe .receive (message: message) 
 pm .receive (message: message) 
 } 

 func receive (message: String ) { 
 print (message) 
 } 
 } 

 class QE : Collogue { 
 var id: String 
 var developer: Developer 
 var pm: PM 

 init (developer: Developer , pm: PM ) { 
 self. id = "QE" 
 self. developer = developer 
 self. pm = pm 
 } 

 func send (message: String ) { 
 developer .receive (message: message) 
 pm .receive (message: message) 
 } 

 func receive (message: String ) { 
 print (message) 
 } 
 } 

 class PM : Collogue { 
 var id: String 
 var developer: Developer 
 var qe: QE 

 init (developer: Developer , qe: QE ) { 
 self. id = "PM" 
 self. developer = developer 
 self. qe = qe 
 } 

 func send (message: String ) { 
 developer .receive (message: message) 
 qe .receive (message: message) 
 } 

 func receive (message: String ) { 
 print (message) 
 } 
 } 

每个角色都需要保留其他角色的实例。 连接是如此紧密，以至于很难进行任何更改。

现在，我们需要调解员来帮助我们简化系统。 定义中介程序是为了帮助涉及的对象相互通信。 这意味着每个对象都与中介而不是其他所有对象进行交互。 这样，除了中介者之外，对象不需要保留对其他对象的引用。 这将使系统解耦。 下图描述了其结构。

让我们开始编写代码。

 protocol Mediator { 
 func send (message: String , sender: Colleague ) 
 } 

 class TeamMediator : Mediator { 
 var colleagues: [ Colleague ] = [] 

 func register (colleague: Colleague ) { 
 colleagues .append (colleague) 
 } 

 func send (message: String , sender: Colleague ) { 
 for colleague in colleagues { 
 if colleague . id != sender . id { 
 colleague .receive (message: message) 
 } 
 } 
 } 
 } 

随着调解人，同事变得如下。

 protocol Colleague { 
 var id: String { get } 
 var mediator: Mediator { get } 
 func send (message: String ) 
 func receive (message: String ) 
 } 

 class Developer : Colleague { 
 var id: String 
 var mediator: Mediator 

 init (mediator: Mediator ) { 
 self. id = "Developer" 
 self. mediator = mediator 
 } 

 func send (message: String ) { 
 mediator .send (message: message, sender: self ) 
 } 

 func receive (message: String ) { 
 print ("Developer received: " + message) 
 } 

 } 

 class QE : Colleague { 
 var id: String 
 var mediator: Mediator 

 init (mediator: Mediator ) { 
 self. id = "QE" 
 self. mediator = mediator 
 } 

 func send (message: String ) { 
 mediator .send (message: message, sender: self ) 
 } 

 func receive (message: String ) { 
 print ("QE received: " + message) 
 } 
 } 

 class PM : Colleague { 
 var id: String 
 var mediator: Mediator 

 init (mediator: Mediator ) { 
 self. id = "PM" 
 self. mediator = mediator 
 } 

 func send (message: String ) { 
 mediator .send (message: message, sender: self ) 
 } 

 func receive (message: String ) { 
 print ("PM received: " + message) 
 } 

 } 

因此，结构如下。

让我们尝试一下。

 //usage 
 let mediator = TeamMediator () 
 let qe = QE (mediator: mediator) 
 let developer = Developer (mediator: mediator) 
 let pm = PM (mediator: mediator) 

 mediator .register (colleague: developer) 
 mediator .register (colleague: qe) 
 mediator .register (colleague: pm) 

 mediator .send (message: "Hello world!", sender: developer) 

另一个例子是流行的通知中心（又名NSNotificationCenter）。 您可以在Internet上找到许多相关代码。