Question

我有一个名为UINavigationController的{{1}}子类。我将其子类化的原因是因为我以编程方式构建UI，对于这个特定的导航类，我需要在其navigationBar的左/右部分有一个特定的按钮。

这就是我在子类中的含义：

NavController

从import UIKit class NavController: UINavigationController { override func viewDidLoad() { super.viewDidLoad() self.view.backgroundColor = UIColor.white self.navigationBar.alpha = 1.0 self.navigationBar.barTintColor = UIColor.navi self.navigationBar.isTranslucent = false self.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.white] // tearing my hair out here let refresh = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.refresh, target: self, action: #selector(doSomething)) self.navigationItem.leftBarButtonItem = refresh } func doSomething() { } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() } }访问navigationItem.leftBarButtonItem是否正确？我的头发用完了。

提前致谢。

Answer 1

快速回复：没有。

navigationItem.leftBarButtonItem是UINavigationController中视图控制器的属性，而不是导航控制器本身。

e.g：

let firstVC = UIViewController()
let firstBarItem = UIBarButtonItem()
firstVC.navigationItem.rightBarButtonItem = firstBarItem
let nc = UINavigationController(rootViewController: firstVC)

导航控制器现在显示firstBarItem

let secondVC = UIViewController()
let secondBarItem = UIBarButtonItem()
secondVC.navigationItem.rightBarButtonItem = secondBarItem

nc.pushViewController(secondVC, animated: true)

导航控制器现在显示secondBarItem

如果您回到firstVC，它会自动显示firstBarItem

Answer 2

是否要在导航栏中显示refresh按钮？但是目前的代码不能这样做，对吧？让我们使用这段代码：

if let navigationItem = navigationBar.items?.first {
    navigationItem.leftBarButtonItem = refresh
}

Answer 3

// Below Code is for Left Side UIBarButtonItem for Navigation Bar
let leftItemBarButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(leftBarButtonTapped))

self.navigationItem.leftBarButtonItem = leftItemBarButton

func leftBarButtonTapped() {
print("Left Bar Button Item")
}

// Below Code is for Right Side UIBarButtonItem for Navigation Bar

let rightItemBarButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(rightBarButtonTapped))

self.navigationItem.rightBarButtonItem = rightItemBarButton

func rightBarButtonTapped() {
print("Right Bar Button Item")
}

如果要使用UIBarButtonItem方法将图像放入导航栏，还有不同的方法

Swift 3 - 向UINavigationController子类添加导航项

3 个答案: