arrays - Firebase 存储异步图像下载顺序不正确

Question

当我尝试从 Firebase 存储中下载一批图像时遇到了问题。基本上，因为文件大小不同，图像没有正确附加到图像数组，导致图像的顺序错误，我想要。下面是代码

import Foundation
import FirebaseStorage

class GalleryCellDetailedData {
    var selectedGallery:String?
    var count:Int

    init(selectedGallery:String?,count:Int){
        self.selectedGallery = selectedGallery
        self.count = count
    }

    func addImages(completion:(data:[NSData])->()){
        var datas = [NSData]()
        let myGroup = dispatch_group_create()

        for i in 0..<count {
            dispatch_group_enter(myGroup)
            getImage(i, completion: { (image:NSData) in
                datas.append(image)
                print("Finish Request \(i)")
                dispatch_group_leave(myGroup)
            })
        }

        dispatch_group_notify(myGroup, dispatch_get_main_queue(), {
          completion(data: datas)
        })
    }

    private func getImage(number:Int, completion:(image:NSData)->()){
        let storage = FIRStorage.storage()

        //Reference to Firebase Profile Picture Storage
        let storageRef = storage.referenceForURL("gs://mannacatering-addcb.appspot.com")
        print("Initiating Image Download")

        let galleryPicRef = storageRef.child("Gallery/\(selectedGallery!)/g\(String(number)).jpg")

        //Download Image
        galleryPicRef.dataWithMaxSize(1 * 1024 * 1024) { (data, error) -> Void in
            if (error != nil) {
                print("fail to download image")
            }

            dispatch_async(dispatch_get_main_queue(), {
                print("Dispatching image")
                completion(image:data!)
            })
        }
    }
}

我将它们分成 2 个独立的函数，因为我试图在一个函数中管理它们，而且顺序也很乱，我认为这可能有效，但显然无效。

Answer 1

与其将数据存储在数组中，不如将其存储在字典中。键可以是数字 i 或者您希望在使用图像时引用它。