Question

我使用以下代码在TabBarController中添加了一个圆形按钮

import UIKit

protocol AddButtonProtocol: class {
   func addButtonIsClicked()
}

 class MainTabBar: UITabBar {

     open var buttonDelegate: AddButtonProtocol?
    private var middleButton = UIButton()

    override open func awakeFromNib() {
        super.awakeFromNib()
        setupMiddleButton()
    }

    override open func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        if self.isHidden {
            return super.hitTest(point, with: event)
        }

        let from = point
        let to = middleButton.center

        return sqrt((from.x - to.x) * (from.x - to.x) + (from.y - to.y) * (from.y - to.y)) <= 39 ? middleButton : super.hitTest(point, with: event)
    }

    func setupMiddleButton() {
        middleButton.frame.size = CGSize(width: 70, height: 70)
        middleButton.backgroundColor = .blue
        middleButton.layer.cornerRadius = 35
        middleButton.layer.masksToBounds = true
        middleButton.center = CGPoint(x: UIScreen.main.bounds.width / 2, y: 0)
        middleButton.addTarget(self, action: #selector(test), for: .touchUpInside)
        addSubview(middleButton)
    }

    @objc func test() {
        print("add button is clicked")
        buttonDelegate?.addButtonIsClicked()

    }
}

看起来像这样。

现在每当我点击该按钮时，都应该触发HomeScreenVCViewController中的方法。所以我已经实现了这样的协议和代理。

import UIKit

class HomeScreenVCViewController: UIViewController {
    var addButtonDelegate: MainTabBar!
    override func viewDidLoad() {
        super.viewDidLoad()
        addButtonDelegate?.buttonDelegate = self
    }

}

extension HomeScreenVCViewController: AddButtonProtocol {
    func addButtonIsClicked() {
        print("protocol is working") // Not getting called
    }
}

但它根本不起作用，当我点击那个圆形按钮时，addButtonIsClicked方法没有被触发。任何帮助将不胜感激。

Answer 1

代表没有被称为b'coz addButtonDelegate是零。您没有初始化addButtonDelegate，因此addButtonDelegate对象为nil

<强>解决方案

您需要将addButtonDelegate设为@IBOutlet，或者需要在viewDidLoad:方法中对其进行初始化。

然后只会调用委托。

示例1

@IBOutlet weak var addButtonDelegate: MainTabBar!

并在viewDidLoad

中

addButtonDelegate.buttonDelegate = self

示例2

创建像

这样的属性

var addButtonDelegate: MainTabBar?

在viewDidLoad初始化addButtonDelegate。

addButtonDelegate = MainTabBar() //or any other initialiser
addButtonDelegate?.buttonDelegate = self

Answer 2

您未在MainTabBar中初始化HomeScreenVCViewController。这就是为什么addButtonDelegate是nil

的原因

var addButtonDelegate: MainTabBar = MainTabBar()
    override func viewDidLoad() {
        super.viewDidLoad()
        addButtonDelegate?.buttonDelegate = self
    }

Answer 3

试试这段代码：

override func viewDidLoad() {
   super.viewDidLoad()
   (tabBarController.tabBar as? MainTabBar)?.buttonDelegate = self
}

ios - 未触发自定义委托方法

3 个答案: