uploading/downloading multiple images the right way? - ios

Question

i'm trying to upload or download images using Nuke(framework for downloading and Caching images) And Firebase to upload images as the backend
for single file it's easy to deal with without any problem
but for multiple ones i don't really know what to do right
i'm having an issues where it don't do it job synchronously
it downloads second image before the first one sometimes
i'll show my way of downloading and uploading multiple images
For download i put the code in for-loop
func downloadImages(completion: (result: [ImageSource]) -> Void){
var images = [ImageSource]()
for i in 0...imageURLs.count-1{
let request = ImageRequest(URL: NSURL(string:imageURLs[i])!)
Nuke.taskWith(request) { response in
if response.isSuccess{
let image = ImageSource(image: response.image!)
images.append(image)
if i == self.imageURLs.count-1 {
completion(result: images)
}
}
}.resume()
}
}
And for uploading where the user chooses the images
form image picker and return it as NSData array
And then perform this code
func uploadImages(completion: (result: [String]) -> Void){
let storageRef = storage.referenceForURL("gs://project-xxxxxxxxx.appspot.com/Uploads/\(ref.childByAutoId())")
var imageUrl = [String]()
var imgNum = 0
for i in 0...imageData.count-1 {
let imagesRef = storageRef.child("\(FIRAuth.auth()?.currentUser?.uid) \(imgNum)")
imgNum+=1
let uploadTask = imagesRef.putData(imageData[i], metadata: nil) { metadata, error in
if (error != nil) {
print("error")
imageUrl = [String]()
completion(result: imageUrl)
} else {
print("uploading")
// Metadata contains file metadata such as size, content-type, and download URL.
let downloadURL = metadata!.downloadURL()?.absoluteString
print(downloadURL)
imageUrl.append(downloadURL!)
if i == imageUrl.count-1{ //end of the loop
print("completionUpload")
completion(result: imageUrl)
}
}
}}
this is good way to do this task ?
what should i do to make each image downloads in order ?
please give me anything that may help example code , link etc ..
Thanks in advance

Answer 1

We highly recommend using Firebase Storage and the Firebase Realtime Database together to accomplish lists of downloads:
Shared:
// Firebase services
var database: FIRDatabase!
var storage: FIRStorage!
...
// Initialize Database, Auth, Storage
database = FIRDatabase.database()
storage = FIRStorage.storage()
Upload:
let fileData = NSData() // get data...
let storageRef = storage.reference().child("myFiles/myFile")
storageRef.putData(fileData).observeStatus(.Success) { (snapshot) in
// When the image has successfully uploaded, we get it's download URL
let downloadURL = snapshot.metadata?.downloadURL()?.absoluteString
// Write the download URL to the Realtime Database
let dbRef = database.reference().child("myFiles/myFile")
dbRef.setValue(downloadURL)
}
Download:
let dbRef = database.reference().child("myFiles")
dbRef.observeEventType(.ChildAdded, withBlock: { (snapshot) in
// Get download URL from snapshot
let downloadURL = snapshot.value() as! String
// Now use Nuke (or another third party lib)
let request = ImageRequest(URL: NSURL(string:downloadURL)!)
Nuke.taskWith(request) { response in
// Do something with response
}
// Alternatively, you can use the Storage built-ins:
// Create a storage reference from the URL
let storageRef = storage.referenceFromURL(downloadURL)
// Download the data, assuming a max size of 1MB (you can change this as necessary)
storageRef.dataWithMaxSize(1 * 1024 * 1024) { (data, error) -> Void in
// Do something with data...
})
})
For more information, see Zero to App: Develop with Firebase, and it's associated source code, for a practical example of how to do this.