Swift UIImage Array from JSON URL - arrays

Question

I try to create an Array of UIImages from a URL Array received from a JSON Request to show them afterwards in a UITableView.
But somehow my UIImage Array stays Empty and is not receiving any Data.
The other Arrays for example memeURL are receiving all Data correct but memePics.count stays on 0.
Would be great if someone could show me what i am doing wrong.
Also if for this task there is a better way on how to do it - it would be also appreciated!
Var:
var memePics: [UIImage] = []
Loop to add Images to Array:
while(i < memeURL.count) {
MemeAPI.requestAPIImageFile(url: memeURL[i]) { (image, error) in
guard let image = image else {
print("PIC IS NIL")
return
}
self.memePics.append(image)
i+=1
}
}
RequestAPIImageFile Function:
class func requestAPIImageFile(url: URL, completionHandler: #escaping (UIImage?, Error?) -> Void) {
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data else {
completionHandler(nil, error)
return}
let downloadedImage = UIImage(data: data)
completionHandler(downloadedImage, nil)
}
task.resume()
}

Answer 1

Add plus line out of callback
self.memePics.append(image)
}
i+=1
and use DispatchGroup to be notified on finish like
let g = DispatchGroup()
memeURL.forEach {
g.enter()
MemeAPI.requestAPIImageFile(url:$0) { (image, error) in
guard let image = image else {
print("PIC IS NIL")
return
}
self.memePics.append(image)
g.leave()
}
}
g.notify(queue:.main) {
print("All done")
}