ios - if else 的快捷方式

Question

我是 swift 的新手，我在以下逻辑中闻到了错误的代码

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    if let dest = segue.destination as? VC1,
        let index =  collectionView?.indexPathsForSelectedItems?.first{
        dest.selection = self.cellLabels[index.row]
    }
    if let dest2 = segue.destination as? VC2,
        let index2 =  collectionView?.indexPathsForSelectedItems?.first{
        dest2.selection = self.cellLabels[index2.row]
    }
    if let dest3 = segue.destination as? VC3,
        let index3 =  collectionView?.indexPathsForSelectedItems?.first{
        dest3.selection = self.cellLabels[index3.row]
    }

}

本质上，我有多个 View Controller ，我试图根据点击的 Cell 访问它们。

为什么我觉得这是糟糕的代码是因为有很多代码重复。有没有更好的方法来构建它？

Answer 1

我会定义协议(protocol):

protocol YourProtocolName: class {
    var selection: String? { get set }  // obviously, use whatever type that is appropriate in your case
}

让您的三个 View Controller 类符合该协议(protocol)，例如:

class VC1: UIViewController, YourProtocolName {
    var selection: String?

    ...
}

然后:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let dest = segue.destination as? YourProtocolName,
        let index =  collectionView?.indexPathsForSelectedItems?.first {
        dest.selection = cellLabels[index.row]
    }
}