Question

我有一个UIBarButtonItem，我想在另一个类中推送ViewController。所以我在viewDidLoad中有这行代码：

      <html>
        <head>
        <meta charset="utf-8">
      </head>
        <body>
        <div  id="image" onmousedown="mouseDown();" onmouseup="mouseUp();">
          <img src="schloss.jpg" draggable="false" />
        </div>

        <script>
        var oldY,oldX;

        function getCoordinates(elem) {
          var LeftPos = elem.offsetLeft;
          var TopPos = elem.offsetTop;
          return {X:LeftPos,Y:TopPos};
        }

        function mouseUp() {
          document.removeEventListener('mousemove', mouseMove, false);
          document.removeEventListener('mouseup', mouseUp, false);
         }

        function mouseDown() {
         document.addEventListener('mousemove', mouseMove, false);
         document.addEventListener('mouseup', mouseUp, false);
         oldY=-1; oldX=-1;
        }   

        function mouseMove(e){
          var iwidth,iheight,newX, newY, diffX, diffY;
          var div=document.getElementById('image');        
          div.style.position = 'absolute';
          if (oldX==-1) {
            diffX=0;diffY=0;}
          else {
            diffY=e.clientY-oldY;diffX=e.clientX-oldX;}
          var p=getCoordinates(div);
          newY=p.Y+diffY;newX=p.X+diffX;
          div.style.top = newY + 'px';div.style.left = newX + 'px';
          oldY=e.clientY;oldX=e.clientX;
          }

      </script>

    </body>
    </html>

这是我的GoToPages课程：

self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(named:"settings"), style: .plain, target: self, action: #selector(GoToPages.goToSettings(_:)))

但是我收到一个错误：无法识别的选择器被发送到实例。

Answer 1

参数target的值必须是实现action的类的实例。

self表示action已在当前类中实现。

Answer 2

我的代码：

导入UIKit

扩展名UIViewController {

@objc func goToPage(_ sender: Any) {

    guard let button = sender as? UIBarButtonItem else {
        return
    }

    switch button.tag {
    case 0:
        let settingsPageView = self.storyboard?.instantiateViewController(withIdentifier: "Notifications")
        self.navigationController?.pushViewController(settingsPageView!, animated: true)
    case 1:
        let settingsPageView = self.storyboard?.instantiateViewController(withIdentifier: "Settings")
        self.navigationController?.pushViewController(settingsPageView!, animated: true)
    default:
        return
    }
}

Answer 3

您应该删除“ GoToPages”。来自#selector(GoToPages.goToSettings(_:))的选择器定义：

#selector(goToSettings(_:))

因为GoToPages.goToSettings是类函数，并且由于您的参数“ target：self”而应该是可以工作的实例方法。这里self指定实例，因此您的选择器必须是实例方法。

如果这不能解决您的问题，请使用self.navigationItem.setRightBarButton(...)而不是直接分配给self.navigationItem.rightBarButtonItem = ...

以下是对我有用的代码：

override func viewDidLoad() {
    super.viewDidLoad()

    let barButtonItem = UIBarButtonItem(image: UIImage(named: "image"),
                                        style: .plain,
                                        target: self,
                                        action: #selector(barButtonItemTapped(sender:))
    navigationItem.setRightBarButtonItems([barButtonItem], animated: true)
}

@objc private func barButtonItemTapped(sender: UIBarButtonItem) {

}

UIBarButtonItem - ＆gt;无法识别的选择器发送到实例（Swift 4）

3 个答案: