Question

我试图获取或设置用于导航左键的功能，但我真的很困惑，因为我设置了图像，但是它们给了我nil值输出，如何解决这是我设置或获取导航键的代码：

var leftNavigationItem: UIImage? {
    get {
        return nil
    }
    set {
        self.navigationItem.hidesBackButton = true
        print(leftNavigationItem)  // output = nil
        self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: newValue, style: .plain, target: self, action: #selector(self.leftNavigationItemAction(_:)))
    }
}

我在viewdidload中使用以下代码：

override func viewDidLoad() {
    super.viewDidLoad()
    title = "Sign In"
    setUI()
    usernameTF.becomeFirstResponder()
    leftNavigationItem = #imageLiteral(resourceName: "back")
}

Answer 1

您明确返回nil，您期望什么？

更改此：

var leftNavigationItem: UIImage? {
    get {
        return nil
    }
    set {
        self.navigationItem.hidesBackButton = true
        print(leftNavigationItem)  // output = nil
        self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: newValue, style: .plain, target: self, action: #selector(self.leftNavigationItemAction(_:)))
    }
}

对此：

var leftNavigationItem: UIImage? {
    set {
        self.navigationItem.hidesBackButton = true
        print(leftNavigationItem)  // output = nil
        self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: newValue, style: .plain, target: self, action: #selector(self.leftNavigationItemAction(_:)))
    }
}

您的代码很疯狂。

当您要“获取”图片时，只需通过self.leftNavigationItem访问即可。

向左获取设置的导航按钮迅速

1 个答案: