swift代理的使用,和oc版本有区别,区别还是蛮大的,不过和oc一样都是用于反向传值:
实现如下:
1,声明两个类
2,实现流程,viewcontroller页面点击按钮进入firstVC页面,然后在firstVC页面修改值,返回把值传到viewcontroller页面
3,具体实现:
a 在firstVC页面声明代理
import UIKit
class FirstViewController: UIViewController {
@IBOutlet weak var textField: UITextField!
var delegate:EditViewControllerDelegate?
var oldStr:String?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
if oldStr != nil {
textField.text = oldStr
}
}
@IBAction func sendAction(_ sender: Any) {
delegate?.edidStr(controller: self, newInfo: textField.text!)
}
@IBAction func disMissAction(_ sender: Any) {
delegate?.editStrDidCancel(controller: self)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
b 声明代理方法
protocol EditViewControllerDelegate {
func edidStr(controller:FirstViewController,newInfo:String)
func editStrDidCancel(controller:FirstViewController)
}
c 代理方法的使用
import UIKit
class ViewController: UIViewController,EditViewControllerDelegate {
@IBOutlet weak var label: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
//页面跳转时
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "EditView"{
let controller = segue.destination as! FirstViewController
//设置代理
controller.delegate = self
//将值传递给新页面
controller.oldStr = label.text
}
}
func edidStr(controller: FirstViewController, newInfo: String) {
label.text = newInfo;
controller.presentingViewController?.dismiss(animated: true, completion: nil)
}
func editStrDidCancel(controller: FirstViewController) {
controller.presentingViewController?.dismiss(animated: true, completion: nil)
}
segue的设置:
作者:稻草人11223