Swift - Downloading Multiple Images Asynchronously [duplicate]

Question

I currently have working code that lets me download a single image. It then puts that image in a imageview inside a collectionview cell.

However, I want to download 2 images from 2 different URLs. Do I need to create another URLSession Task, or can I simply download 2 images with the same session?

let url = URL(string: "www.example.com/image.jpg")
let task = URLSession.shared.dataTask(with: url!) { data, response, error in 
guard let data = data, error == nil else { return }

DispatchQueue.main.async() {
    cell.postImage.image = UIImage(data: data) 
    }
}

Edit: Not sure why Leo marked my question as a duplicate. I already saw that post and it only loads a single image. My questions is in regards to the correct way of downloading multiple images smh.

my recommendation is to use a extension on your imageview . and there are few good 3rd party libraries that will make it more easy — Kamal Upasena
– Kamal Upasena, Commented Jan 23, 2018 at 12:44
Take a look at LazyTableImages how to use a simple asynchronous download manager. — vadian
– vadian, Commented Jan 23, 2018 at 13:09

Kingalione · Accepted Answer · 2018-01-23 13:21:30Z

2

I would recommend you to use a third party library for this purpose. What I can suggest is the SDWebImage Library: SDWebImage

The usage of the library is pretty simple. Here is an example:

import SDWebImage

imageView.sd_setImage(with: URL(string: "http://www.test.com/path/to/image.jpg"), placeholderImage: UIImage(named: "placeholder.png"))

It handles the asynch downloading itself, so you don't need to worry about this stuff anymore. Also it has a clever caching system integrated, that means if the image is downloaded once, it will not download the same image again.

answered Jan 23, 2018 at 13:21

Kingalione

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Duncan C · Accepted Answer · 2018-01-23 20:52:17Z

1

You want a separate data task per image. Note that whether you have to create a separate data task (you do) is different than whether you need to create a separate URLSession object. (For simple tasks using the shared session object is fine.)

You can also use a 3rd party library like the others are suggesting. There are both pros and cons to using 3rd party frameworks.

edited Jan 23, 2018 at 20:52

answered Jan 23, 2018 at 13:40

Duncan C

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