How to save image

Question

I want to save image with userdefaults and use it in another view with this code but it shows an error .

UserDefaults.standard.set(img , forKey : "simg")

please help me

First of all don't misuse `UserDefaults` as temporary data storage between view (controllers), second of all if you get an error the type of `img` is not property list compliant. — vadian, Jul 07 '17 at 18:58
The better is to save the image to documents then save the path to the image in `UserDefaults`, which will be an easy task. — Mo Abdul-Hameed, Jul 07 '17 at 18:59
Check the last section of [this answer](https://stackoverflow.com/a/21810380/4763963). — Mo Abdul-Hameed, Jul 07 '17 at 19:07
As the developer you are supposed to know the static type of `img` — vadian, Jul 07 '17 at 19:09
@MJP - Are you trying to "save" the image so you can re-load and re-use it the next time the user runs the app? Or are you just trying to select an image in one place in your app, and then show it in another place? — DonMag, Jul 07 '17 at 19:39

Mozahler · Accepted Answer · 2017-07-07T20:27:31.543

This is how I would do it. You have multiple places to save it to, the user's Documents folder is usually best:

func cacheImageAsPNG(image: UIImage, localID: String) {
    let userDocumentsURL = URL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0])
    if let imageData = UIImagePNGRepresentation(image) {
        let filename = userDocumentsURL.appendingPathComponent("\(localID).png")

        if  FileManager.default.createFile(atPath: filename.path, contents: imageData, attributes: nil) {
            print("wrote file:\n\(filename.path)")
        } else {
            print("couldn't write the file:\n\(filename.path)")
        }
    }
}

if you want it erased by the system during times of peak memory usage, the cache directory is a better place:

 let cachesPath = NSSearchPathForDirectoriesInDomains(.cachesDirectory, .userDomainMask, true).last!

Edit: Retrieving the Image

func cachedImage(localID: String) -> UIImage? {
    let userDocumentsURL = URL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0])
    let cachePath = userDocumentsURL.appendingPathComponent("\(localID).png")

    return UIImage(named: cachePath.path)
}

You should probably show how to read the image in from the saved file as well. — wottle, Jul 07 '17 at 19:37
I agree. Done. I was waiting to see how saving worked out so I could adjust my answer. But it's best to leave the answer complete. — Mozahler, Jul 07 '17 at 20:29

score 0 · Answer 2 · answered Jul 07 '17 at 19:04

0

You can't save a UIImage directly to NSUserDefaults. You could save it as NSData, but it really is not advisable. NSUserDefaults is meant to store small bits of information in key value pairs. If you start throwing images in there, you could overload the space reserved for it. The contents of the NSUserDefaults is written to a plist. I believe any time you access the user defaults, it reads the whole file. If you put large images in there, it will cause a lot of unnecessary I/O.

If you still decide to do it (not recommended), here is a good post on getting an NSData object from the image.

answered Jul 07 '17 at 19:04

wottle

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I take image in view and i want to show that image in another view – Mahdi Jamshidpour Jul 07 '17 at 19:07
1

If you are just looking to save an image to be used on another view, I would do as @Mozahler suggests in his answer and save it to the user's Documents directory. – wottle Jul 07 '17 at 19:36

score 0 · Answer 3 · answered Jul 07 '17 at 19:45

As others have said, don't save images to user defaults. It's only intended for small bits of data.

If all you want to do is to pass an image in another view controller, and you don't care about making the image persist if the user quits and re-launches the app, just pass the image in prepareForSegue.

How to save image

3 Answers3

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