Question

我是swift的新手，我在下面的逻辑中发现了一个糟糕的代码

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]
    }

}

基本上，我有多个视图控制器，我试图触及它，具体取决于哪个Cell被点击。

为什么我觉得这是错误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

我定义了协议：

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

让您的三个视图控制器类符合该协议，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]
    }
}

Answer 2

clickedLink

Answer 3

我会使用父类来处理所有三个ViewController类，并将共享变量放在父类中。 e.g。

class ParentViewControllerClass: UIViewController{
    var selection: Int?
}

class VC1: ParentViewControllerClass{
}
class VC2: ParentViewControllerClass{
}
class VC3: ParentViewControllerClass{
}

然后你应该能够分配一次值。像：

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

这样，无论调用三个子视图控制器中的哪一个，都将满足该语句

Answer 4

试试这个：

override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    self.performSegue(withIdentifier: "segueIdentifier", sender: collectionView.cellForItem(at: indexPath))
}

如果不这样做的话

4 个答案: