ios - 从字典中调用图像时出错

Question

我正在尝试创建图像字典，其名称如下。我收到以下错误(显示为错误行上方的注释)。

ViewController.swift

var selectedImages = [String : UIImage ]()

let cityImages: [String : UIImage] = [ "City00" : UIImage(named: "city_00")!  , "City01" :UIImage(named: "city_01")!, "City02" : UIImage(named: "city_02")!]


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
        as! CollectionViewCell

    // Ambiguous reference to member 'subscript'
    cell.imageView?.image = self.selectedImages[(indexPath as NSIndexPath).item]

    return cell
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "showOptions"
    {
        let indexPaths = self.collectionView!.indexPathsForSelectedItems!
        var indexPath = indexPaths[0] as IndexPath
        let CityVC = segue.destination as! CitySelectViewController

        // Ambiguous reference to member 'subscript'
        CityVC.imageSelected = self.selectedImages[(indexPath as NSIndexPath).item]
    }

如何消除这些错误？

这是CitySelectViewController.swift

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return self.imageSelected.count

}


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
        as! CityCollectionViewCell

    cell.imageView?.image =  imageSelected[(indexPath as NSIndexPath).row]

    return cell
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)

    cellImage = imageSelected[(indexPath as NSIndexPath).row]
    cellImageName = imageSelected[(indexPath as NSIndexPath).row]
}

Answer 1

字典与 UICollectionView 和 UITableView 不太匹配，因为它们是无序的；这意味着您不能使用整数索引进行索引(除非您使用 Int 作为键，但这实际上是一个数组)并且如果您枚举键或值，则返回这些键或值的顺序未定义。

您添加的第二个 View Controller 澄清了您真正的问题；你想向第二个 View Controller 发送多条信息。我仍然不完全清楚第二个 View Controller 的目的是什么，并且由于您使用的是另一个 Collection View ，我假设您希望能够通过多个选定的城市，尽管您的 segue 似乎是在单个选择上触发的，所以这暂时行不通。我已经展示了通过多项选择的代码，无论如何

您应该创建一个struct 来保存您的城市数据并使用该结构的数组:

struct City {
    var name: String
    var imageName: String
}

class firstViewController: UIViewController // Or UICollectionViewController 

let cities = [City(name:"City00", imageName:"city_00"),
              City(name:"City01", imageName:"city_01"),
              City(name:"City02", imageName:"city_02")]


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
    as! CollectionViewCell

    let city = self.cities[indexPath.item]

    cell.imageView?.image = UIImage(named:city.imageName)

    return cell
}


override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "showOptions" {
        if let indexPaths = self.collectionView!.indexPathsForSelectedItems {
            if let cityVC = segue.destination as? CitySelectViewController {
                var selectedCities = [City]()
                for indexPath in indexPaths {
                    selectedCities.append(self.cities[indexPath.item])
                }
                cityVC.selectedCities = selectedCities
            }
        }
    }
}

现在，在您的 CitySelectViewController

class CitySelectViewController {

    var selectedCities = [City]()

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.selectedCities.count
    }


    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
    as! CityCollectionViewCell

        let city = self.selectedCities[indexPath.item]
        cell.imageView?.image =  UIImage(named:city.imageName)

        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let city = self.selectedCities[indexPath.item]
        cellImage = UIImage(named: city.imageName)
        cellName = city.name
    }
}