使用通知机制在不同页面传送数据

在两个页面之间传送数据,可以使用通知机制实现.

例如, 点击页面A的按钮, 数据由页面A -- > 页面B , 操作步骤:

1. 定义页面A按钮的点击事件:

 @IBAction func save(_ sender: Any) {     
        self.dismiss(animated: true) { () -> Void in
            let dataDict = ["username" : "123"]
            //采用通知机制将dataDict传给页面B
            NotificationCenter.default.post(name: NSNotification.Name(rawValue: "RegisterCompletionNotification"), object: nil, userInfo: dataDict)
        }
    }

2. 在页面B注册通知和回调方法:

import UIKit
class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        //注册通知 RegisterCompletionNotification
        NotificationCenter.default.addObserver(self, selector: #selector(ViewController.register(_:)), name: NSNotification.Name(rawValue: "RegisterCompletionNotification"), object: nil)
    }

    //定义回调方法
    func register(_ notification:Notification) {
        let theData = notification.userInfo!
        let username = theData["username"] as! String
        NSLog("username = %@", username)
    }

    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        NotificationCenter.default.removeObserver(self)
    }

}