Swift—闭包、代理实现反向传值(附具体代码)

在iOS开发过程中,我们经常会有这样的一个需求,假设有两个界面:ViewControllerA、ViewControllerB,我们从ViewControllerA进入到ViewControllerB,想把ViewControllerB中的值传回ViewControllerA(反向传值问题),下面介绍闭包和代理两种方法来处理.

这两种方法其实实现的思路是非常类似的,大致分为三个过程:定义、调用、实现.代理传值多一个设置代理的步骤.

闭包传值:

        定义:从哪个界面传值,就在哪个界面定义,本案例中是ViewControllerB.

        调用:从哪个界面传值,就在哪个界面调用,本案例中是ViewControllerB.

        实现:想传递到哪个界面,就在哪个界面实现,本案例中是ViewControllerA.

下面是具体实现代码:

        ViewControllerA:

1.  
   import UIKit
2.  
   class ViewControllerA: UIViewController{
3.  
   override func viewDidLoad() {
4.  
   self.view.backgroundColor = .white
5.  
   }
6.  
   override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
7.  
   let viewB = ViewControllerB()
8.  
   self.present(viewB,animated: true)
9.  
   //闭包实现
10.  
    viewB.closure = { age,sentense in
11.  
    print("\(age)------\(sentense)")
12.  
    }
13.  
    }
14.  
    }

        ViewControllerB:

1.  
   import UIKit
2.  
   class ViewControllerB :UIViewController{
3.  
   //闭包定义
4.  
   var closure:((Int,String)->())?
5.  
   override func viewDidLoad() {
6.  
   self.view.backgroundColor = .brown
7.  
   }
8.  
   override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
9.  
   //闭包调用
10.  
    closure!(1314,"Hyx Love Hxy")
11.  
    self.dismiss(animated: true)
12.  
    }
13.  
    }

代理传值:

         ViewControllerA:        

1.  
   import UIKit
2.  
   class ViewControllerB :UIViewController{
3.  
   //代理定义
4.  
   var delegate:Transmit?
5.  
   override func viewDidLoad() {
6.  
   self.view.backgroundColor = .brown
7.  
   }
8.  
   override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
9.  
   //代理调用
10.  
    delegate?.transmitData(year: 1314, sentense: "Hyx Love Hxy")
11.  
    self.dismiss(animated: true)
12.  
    }
13.  
    }
14.  
    //协议
15.  
    protocol Transmit{
16.  
    func transmitData(year:Int,sentense:String)
17.  
    }

        ViewcontrollerB:

1.  
   import UIKit
2.  
   class ViewControllerB :UIViewController{
3.  
   //代理定义
4.  
   var delegate:Transmit?
5.  
   override func viewDidLoad() {
6.  
   self.view.backgroundColor = .brown
7.  
   }
8.  
   override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
9.  
   //代理调用
10.  
    delegate?.transmitData(year: 1314, sentense: "Hyx Love Hxy")
11.  
    self.dismiss(animated: true)
12.  
    }
13.  
    }
14.  
    //协议
15.  
    protocol Transmit{
16.  
    func transmitData(year:Int,sentense:String)
17.  
    }

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