Cache Image swift - swift

Question

I try cache An image from An URL from my firebase storage. if I Print my url in function "downloadImage" I can see that I get image URL. But I Print my url in my function getImage, then nothing display.
Here I my Image Service:
import Foundation
import UIKit
import Firebase
class ImageService {
static let cache = NSCache<NSString, UIImage>()
static let storage = Storage.storage()
static let db = Firestore.firestore()
// Downloading image with URL
static func downloadImage(withURL url:URL, completion: #escaping (_ image:UIImage?, _ url:URL)->()) {
let dataTask = URLSession.shared.dataTask(with: url) { data, responseURL, error in
var downloadedImage:UIImage?
if let data = data {
downloadedImage = UIImage(data: data)
}
if downloadedImage != nil {
cache.setObject(downloadedImage!, forKey: url.absoluteString as NSString)
}
DispatchQueue.main.async {
completion(downloadedImage, url)
}
}
dataTask.resume()
}
// Get the downloaded image
static func getImage(withURL url:URL?, completion: #escaping (_ image:UIImage?, _ url:URL)->()) {
if let _url = url {
if let image = cache.object(forKey: _url.absoluteString as NSString) {
completion(image, _url)
print("HEJSAN\(String(describing: url))")
} else {
downloadImage(withURL: _url, completion: completion)
}
}
}
// Set the retrieved image for the UIImageView
static func setImage(imageView image: UIImageView, imageURL url: String) {
getImage(withURL: URL(string: url)) { retrievedImage, error in
image.image = retrievedImage
}
}
This how I try display it in my VC:
override func viewDidLoad() {
super.viewDidLoad()
ImageService.setImage(imageView: logoImage, imageURL: "https://firebasestorage.googleapis.com/v0/b/shutappios.appspot.com/o/LogoImage%2FShutAppLogo.jpg?alt=media&token=13216931-418f-486a-9702-2985b262ab08")
}

Answer 1

I'm not sure if understood well your question but based on what you said it is normal that the getImage when it is called the first time that will execute downloadImage because there will be no image in the cache yet but it will have an image the second time called. maybe the issue here is that you are trying to get the image from the cache before the downloadImage completed because its code is happening on the background async does mean if you are trying to get the cash after that straightaway without waiting. More likely it will not be ready so if you want to make sure that is not going to happen I think you need to add completion to your setImage func something like this:
static func setImage(
imageView image: UIImageView,
imageURL url: String,
completion: (() -> ())? = nil) {
getImage(withURL: URL(string: url)) { retrievedImage, error in
image.image = retrievedImage
completion?()
}
}
this example it will print your log from the getImage as expected the first time is downloading the second is getting from the cache.
ImageService.setImage(imageView: imageView, imageURL: imageURL) {
ImageService.setImage(imageView: self.imageView, imageURL: imageURL)
}
Please note this just an example to give you idea about what could be the issue behind this I hope it will help you!