显示在集合视图控制器之间选择的图像

Question

我有 structs 如下 First Collection View Controller

struct Area{
    var name = String()
    var image = String()  
}
var area = [Area]()

并在 Second Collection View Controller

struct AreaSelected {
   var imageSelected = String()
}
 var areaSelected = [AreaSelected]()

我想在 Second Collection View Controller 中显示从 First Collection View Controller 中选择的图像。

所以我这样做是为了将它们导航到位于 didSelectItemAt indexPath

的 Second Collection View Controller

   let indexPaths = self.areaCV!.indexPathsForSelectedItems!
   var indexPath = indexPaths[0] as IndexPath
   let detailViewController = self.storyboard?.instantiateViewController(withIdentifier: "SVC") as? SecondViewController
   detailViewController?.areaSelected = [self.area[(indexPath as NSIndexPath).item]]

他们我得到以下编译器错误

Cannot convert value of type 'Area' to expected element type 'AreaSelected'

如何摆脱这个错误？

Answer 1

基本上

 let selectedArea = self.area[(indexPath as NSIndexPath).item]
 detailViewController?.areaSelected = [AreaSelected(imageSelected: selectedArea.name)]

PS：您在不同的视图控制器中使用了不同的（不兼容的）类型，因此绝对不能直接将其分配给彼此。

PSS：在 ViewController 之间的 CellSelected 上设置 segue 更容易、更清晰、更好，并在 func prepare(for segue:UIStoryboardSegue, sender: Any?)

中分配 areaSelected

Answer 2

错误消息很清楚，您的第一个结构类型为：FirstCollectionViewController.Area，第二个结构类型为SecondCollectionViewController.AreaSelected。两者就像 Int 和 String 一样不同，你不能将一个分配给另一个，就像你不能做 let number: Int = "Of course no" 一样。但是你可以定义一个通用类型：

protocol AreaDescription { 
    var image: String { get }
}

class FirstVC: ... {

    struct Area: AreaDescription {
        var name: String
        var image: String
    }
}

class SecondVC: ... {

    struct AreaSelected: AreaDescription {
        var name: String
        var image: String
    }
}

并将您的属性设置为：

var areaSelected = [AreaDescription]()

显示在集合视图控制器之间选择的图像

Displaying image selected between collection view controllers

ios

swift

xcode

struct

didselectrowatindexpath