navigation bar button and items not showing in swi

问题:

am using navigation bar programmatically in swift, but am not able to show the bar button items in navigation bar, this is the code what I did

override func viewDidLoad() {
        super.viewDidLoad()

  let navBar: UINavigationBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: 420, height: 65))
        self.view.addSubview(navBar)

        navBar.backgroundColor = hexStringToUIColor("4DC8BD")

        let navigationItem = UINavigationItem()

       self.title = "Transport APP"

        let btn1 = UIButton(type: .custom)
        btn1.setImage(UIImage(named: "Menu1"), for: .normal)
        btn1.frame = CGRect(x: 30, y: 30, width: 30, height: 30)
        btn1.addTarget(self, action: #selector(HomeViewController.menubuttonclick(_:)), for: .touchUpInside)
        let item1 = UIBarButtonItem(customView: btn1)


         self.navigationItem.setRightBarButtonItems([item1], animated: true)

}

    @IBAction func menubuttonclick(_ sender:UIBarButtonItem )
    {

        print("this menu button click")

    }

I can try many ways but am not getting the results how to show show bar button item in navigation bar,

回答1:

You should add UINavigationItem to your UINavigationBar and in item1 need to be added in navitem Look at below code

    let navitem = UINavigationItem()
    navitem.rightBarButtonItem = item1
    navBar.setItems([navitem], animated: true)

回答2:

While the other mentioned solutions definitely work for programmatically defining the navigation item, some would prefer a storyboard solution. I searched for a Swift 4, Xcode 9 storyboard solution and was unable to find one, so I will show my solution.

Here is a screenshot of my storyboard before adding the bar button item.

The issue I was having is that while the Shops tableview is embedded in the navigation controller, and adding a bar button item was no issue; the Employees tableview is pushed via the navigation controller in the didSelectRowAt function.

extension ShopsViewController: UITableViewDelegate {
  func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let selectedShop = fetchedResultsController.object(at: indexPath)
    let st = UIStoryboardname: "Main", bundle: Bundle.main)
    let vc = st.instantiateViewController(withIdentifier: "EmployeeViewController") as! EmployeeViewController

    vc.shop = selectedShop

    self.navigationController?.pushViewController(vc, animated: true)
  }
}

The result is that I could not drag a bar button item from the storyboard. When I tried, the item would end up in the tab bar at the bottom.

I found an article that suggested embedding the second view controller in a navigation controller, but that adds other levels of complexity that I wanted to avoid. The work around I found is to drag a navigation item to the navigation bar area, and then you can add a bar button item with no problems.

Here is the result:

I know there is a lot of debate whether storyboards or programmatic layout is better. While I am still very much a beginning iOS developer and cannot personally speak to that, I am finding that sometimes the storyboard solution fits the problem best. I hope this helps other beginners.

回答3:

Swift 3+: Define the barbutton.

//:: Left bar items
     lazy var leftBarItem: Array = { () -> [UIBarButtonItem] in
            let btnBack = UIButton(type: .custom)
            btnBack.frame = kBAR_FRAME
            btnBack.addTarget(self, action: #selector(clickOnBackBtn(_:)), for: .touchUpInside)
            let item = UIBarButtonItem(customView: btnBack)
            item.tag = 3
            return [item]
    }()

Add this line into viewDidLoad

 self.navigationItem.setLeftBarButtonItems(self.leftBarItem, animated: true)

Bar Button Action

@objc func clickOnBackBtn(_ sender: Any){

    }

回答4:

if you've already created UINavigationController() you can set navigation items using self.navigationItem like this (in viewDidLoad function):

self.navigationItem.title = "Transport APP"
self.navigationItem.rightBarButtonItem = item1

but if you need to know how to create UINavigationController() for a view, you can do this in AppDelegate class:

let myView = ... //initial your view controller
let nav = UINavigationController()
nav.viewControlles = [myView]

and then everywhere you need, you should push nav view.