ios - 从 View Controller 发布到另一个ViewController时，NotificationCenter第一次无法正常工作

我有两个ViewController1和ViewController2。
我正在将通知从ViewController1发布到ViewController2，但在第一次发布时，NotificationCenter第一次不工作。
当我从ViewController2返回ViewController1，然后再次尝试移动ViewController2，则时间通知中心正在工作，
//视图控制器1.swift

import UIKit

class ViewController1: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

}

//Move to next VC
@IBAction func nextButtonClicked(_ sender: Any) {

    NotificationCenter.default.post(name: Notification.Name("callMethodPrint1FromVC2"), object: nil)

    let storyBoard = UIStoryboard(name: "Main", bundle: nil)
    let vc2 = storyBoard.instantiateViewController(withIdentifier: "ViewController2Id") as? ViewController2
    navigationController?.pushViewController(vc2!, animated: true)

  }
}

//视图控制器2.swift

import UIKit

class ViewController2: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.


}

override func viewWillAppear(_ animated: Bool) {
    //Recieve notification
    NotificationCenter.default.addObserver(self, selector: #selector(self.print1Method(notification:)), name: Notification.Name("callMethodPrint1FromVC2"), object: nil)
}

@objc func print1Method(notification: Notification) {

    print("Notification came from VC 1")
}

@IBAction func backToVC1(_ sender: Any) {

    let storyBoard = UIStoryboard(name: "Main", bundle: nil)
    let vc2 = storyBoard.instantiateViewController(withIdentifier: "ViewController1Id") as? ViewController1
    navigationController?.pushViewController(vc2!, animated: true)
}

 //Remove notification object
deinit {

    NotificationCenter.default.removeObserver(self, name: Notification.Name("callMethodPrint1FromVC2"), object: nil)
}

}

实际产量：
当我第一次和每次将ViewController1移动到ViewController2时，ViewController2中的print1Method方法必须调用。
但它的工作速度并没有那么快。
我的代码中是否有Anu问题，或者我遗漏了什么？

最佳答案

您正在初始化视图控制器之前发布通知。
调用vc2方法不需要发布通知。相反，直接调用方法。
在VC1中

@IBAction func nextButtonClicked(_ sender: Any) {

     let storyBoard = UIStoryboard(name: "Main", bundle: nil)
     let vc2 = storyBoard.instantiateViewController(withIdentifier:"ViewController2Id") as ViewController2
     vc2.print1Method()
     navigationController?.pushViewController(vc2!, animated: true)

  }
}

在VC2中

func print1Method() {

     print("Method called from VC 1")
 }

同样对于后退按钮，你做得不对。只需从堆栈中弹出视图控制器

 @IBAction func backToVC1(_ sender: Any) {

     self.navigationController?.popViewController(animated: true)
 }

关于ios - 从 View Controller 发布到另一个ViewController时，NotificationCenter第一次无法正常工作，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/58074114/