导航栏不可见迅速

Question

我正尝试通过swift 4以编程方式在xcode中设置navigationBar。我也希望显示带有标题的后退按钮。

按照我的逻辑，我的应用似乎没有任何显示。我不知道什么是不对的。请帮忙。

import UIKit

class SellBaseViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

       self.setNavigationBar()
           setLayout()

    }

    func reload() {
        self.viewDidLoad()
    }
    func setNavigationBar() {
        let width = self.view.frame.width
        let navigationBar: UINavigationBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: width, height: 44))
        self.view.addSubview(navigationBar);
        let navigationItem = UINavigationItem(title: "Navigation bar")
        let doneBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.done, target: nil, action: #selector(selectorX))
        navigationItem.rightBarButtonItem = doneBtn
        navigationBar.setItems([navigationItem], animated: false)
    }

    func setLayout(){

    }
   @objc func selectorX() {

    }
}

Answer 1

尝试将您的代码放入viewWillAppear。

override func viewWillAppear(_ animated: Bool) {

        super.viewWillAppear(animated)
        self.setNavigationBar()
           setLayout()