使用闭包和代理和Segue进行反向传值

Posted 2020-09-16 auvxx

import UIKit

class FirstViewController: UIViewController, SecondViewControllerDelegate {

    @IBOutlet weak var showTextLabel: UILabel!
    @IBOutlet weak var showDelegateTextLabel: UILabel!
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    
    //点击按钮跳转到SecondViewController
    @IBAction func tapGoSecondViewController(sender: UIButton) {
        //从storyboard上加载SecondViewController
        let secondVC = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle()).instantiateViewControllerWithIdentifier("secondViewController") as! SecondViewController
        //实现回调，获取回调回来的值 （闭包）
        secondVC.backClosure = {
            (backStr: String) -> Void in
            self.showTextLabel.text = backStr
        }
        secondVC.delegate = self
        //跳转到SecondViewController
        self.navigationController?.pushViewController(secondVC, animated: true)
    }
    //MARK: - SecondViewControllerDelegate(代理)
    func fetchBackString(str: String) {
        self.showDelegateTextLabel.text = str
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

import UIKit

 

//定义闭包类型（特定的函数类型函数类型）

typealias InputClosureType = (String) -> Void

 

protocol SecondViewControllerDelegate: NSObjectProtocol{

    func fetchBackString(str: String)

}

 

class SecondViewController: UIViewController {

     

    @IBOutlet weak var inputTextField: UITextField!

    //接收上个页面传过来的闭包块

    var backClosure: InputClosureType?

    weak var delegate: SecondViewControllerDelegate?

     

    override func viewDidLoad() {

        super.viewDidLoad()

 

        // Do any additional setup after loading the view.

    }

 

    @IBAction func tapBackButton(sender: UIButton) {

        if self.backClosure != nil {

            if let tempString = self.inputTextField.text {

                self.backClosure!(tempString)

            }

        }

        self.navigationController?.popViewControllerAnimated(true)

    }

     

    @IBAction func delegateBackMethod(sender: UIButton) {

        if self.delegate != nil {

            if let tempString = self.inputTextField.text {

                delegate!.fetchBackString("代理返回数据:\(tempString)")

            }

        }

        self.navigationController?.popViewControllerAnimated(true)

    }

     

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}

 

利用Segue进行转场传值

---

 

正向跳转

segue正向转场是prepareForSegue

在源VC中->NavigationViewController在Segue的属性中选择show（Xcode7.2没有show detail），会有返场btn，将VC push进下一个场景。源VC中用prepareForSegue进行设置，在方法中确定目的VC，然后对目的VC中的属性进行赋值或传递方法。

反向转场

模态展现(modal)的视图系统不提供返回按钮。我们需要定义一个反向转场，可以用模态视图退场。

在目的视图定义这个函数

@IBAction func close(segue:UIStoryboardSegue){

里面放传递的数据

}

在跳转VC中按control拖btn到exit，选择close。

反向转场用performSegueWithIdentifier.

btn拖到exit->出口执行目的地VC中的自定义函数

@IBAction func close(segue:UIStoryboardSegue)

{

let sourceVC = segue.sourceViewController as 源VC

（获取sourceVC中的对象或者数据后在destVC中进行处理）

}