How to Load image very fast if image is big size in ios swift

Question

I have big image it came from Api then how to load it fast . It Take too much time to load

  let data = NSData(contentsOf: NSURL(string: self.imageFile)! as URL)

            if data == nil{
            }

            else{

                DispatchQueue.main.async() {
        self.imageShow.image = UIImage(data: data! as Data)
                }
            }

this is my code can any one suggest me

**Never ever** load data synchronously from a remote `URL` with `Data(contentsOf`. Use asynchronous `URLSession` or similar API. And don't use `NSURL / NSData` in Swift 3+ — vadian, Apr 10 '18 at 08:57
use SDWebImage library for loading images even big and can cache it too. — MRizwan33, Apr 10 '18 at 08:57
Comments/answers saying about thread - it's not yet clear if code running on main thread, maybe it's already running asynchronously, if no, then you have to change it. Also things like `NSURL(string: self.imageFile)!` are very dangerous, you should learn basic stuff like optionals, networking. — Injectios, Apr 10 '18 at 09:06

Dheeraj D · Accepted Answer · 2018-04-10T09:54:06.700

2

You can use this code to Async Download Image.

    if let url = self.imageFile{

    let url = URL(string: self.imageFile)

        let task = URLSession.shared.dataTask(with: url!) { data, response, error in
            guard let data = data, error == nil else { return }

            /**CHECK 404 HERE*/
            if let httpResponse = response as? HTTPURLResponse {
                if httpResponse.statusCode == 400 {
                    //YOUR CODE HERE
                return
                }
            }


            DispatchQueue.main.async() {    // execute on main thread
                self.imageShow.image = UIImage(data: data)
            }
        }

    task.resume()

    }else{

        DispatchQueue.main.async() {    // execute on main thread
         self.viewImageType.isHidden = true
        }
    }

BETTER NOT TO DEPEND ON THIRD PARTY LIBRARIES

edited Apr 10 '18 at 09:54

answered Apr 10 '18 at 09:02

Dheeraj D

4,386
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and how can i call this – Anurag Mishra Apr 10 '18 at 09:07
@Anurag Mishra Just replace the code. You need to add a progress view to show the network activity. – Dheeraj D Apr 10 '18 at 09:09
@Anurag Mishra Please have a look to updated answer. – Dheeraj D Apr 10 '18 at 09:29
it is also taking time my image is big – Anurag Mishra Apr 10 '18 at 09:35
1

If your image is Big then it is not possible to download it without fast internet connection. What I have shared is a async download code. Which will not stuck your UI. Better to keep thumbnail image or small image at server. Thanks. @Anurag Mishra – Dheeraj D Apr 10 '18 at 09:36
@Anurag Mishra If you use code shared by me would do same: download image and then show – Dheeraj D Apr 10 '18 at 09:43
Can you suggest me how to download image but not in phone – Anurag Mishra Apr 10 '18 at 09:43
You can create background task to download in background and store it in document directory. And then use it whenever you want to show it on view. Refer this https://stackoverflow.com/questions/6238139/ios-download-and-save-image-inside-app – Dheeraj D Apr 10 '18 at 09:45
this error are coming when i call httpResponse.statusCode == 400 UIView.hidden must be used from main thread only self.viewImageType.isHidden = true – Anurag Mishra Apr 10 '18 at 09:50

Ankit Jayaswal · Answer 2 · 2018-04-10T09:10:54.807

1

You can use NSOperationQueue to load your image on background thread and then load image on image view on main thread. You can achieve this by:

    let myQueue = OperationQueue()
    myQueue.addOperation { // Load image on background thread
        if let urlString = URL(string: self.imageFile) {
            do {
                let data = try Data(contentsOf: urlString)
                DispatchQueue.main.async { // Load image on main thread
                    self.imageShow.image = UIImage(data: data)
                }
            } catch {
                print("not able to load image")
            }
        }
    }

edited Apr 10 '18 at 09:10

answered Apr 10 '18 at 09:05

Ankit Jayaswal

5,549
3
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how to call if there is 404 url also – Anurag Mishra Apr 10 '18 at 09:22
I am getting your point as like image is not present at given url. In that case `let data = try Data(contentsOf: urlString)` will throw it in catch block and you can assign a default image there – Ankit Jayaswal Apr 10 '18 at 09:27
it is also taking time to load my image file is big – Anurag Mishra Apr 10 '18 at 09:31

How to Load image very fast if image is big size in ios swift

2 Answers2