Swift - saving and retrieving images from userDefaults

Question

I'm trying to save images retrieved from Parse.com like this:

                    let userImageFile = object["Image"] as PFFile
                    userImageFile.getDataInBackgroundWithBlock {
                        (imageData: NSData!, error: NSError!) -> Void in
                        if error == nil {
                            image = UIImage(data:imageData)
                            let imageToSave:NSData = UIImagePNGRepresentation(image)
                            self.saveImage(intRandomNumb, retImage: imageToSave)
                        }
                    }

where the saveImage-function looks like this:

func saveImage(imagepath:Int, retImage:NSData){

    println("image is being saved")

    let defaults = NSUserDefaults.standardUserDefaults()
    let imagePathName = "\(imagepath)"

    defaults.setObject(retImage, forKey: imagePathName)

}

and later, I'm trying to display this image like this:

        var point = gestureRecognizer.locationInView(self.tv)
        if let indexPath = self.tv.indexPathForRowAtPoint(point)
        {
            let data = mainList[indexPath.row] as SecondModel
            let fileRef = data.fileReference
            let intFileRef = Int(fileRef)
            println(intFileRef)

            let defaults = NSUserDefaults.standardUserDefaults()
            let usedKeyName = "\(intFileRef)"

            if let photo = defaults.objectForKey(usedKeyName) as? UIImage {
                println("Image created")
                let photo = defaults.objectForKey(usedKeyName) as UIImage

                var imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height))
                imageView.image = photo
                self.view.addSubview(imageView)
            }

and the "Image created" never gets printed which means the retrieving somehow doesn't work. I'm not quite sure if you're able to save images to the userdefaults like I've done here, but that was the best I could come up with, and I couldn't find any previous questions like this for Swift.

Any suggestions on how to proceed would be appreciated.

SOLUTION: The problem was that I tried to load the image directly as a UIImage. I also had to convert the NSData to a UIImage, this all happens in the last section of the code displayed above. Finally my code looks like this:

        if let photo = defaults.objectForKey("\(intFileRef)") as? NSData {
            println("Image created")
            let photo = defaults.objectForKey("\(intFileRef)") as NSData
            let imageToView:UIImage = UIImage(data: photo)

            var imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height))
            imageView.image = imageToView
            self.view.addSubview(imageView)
        }

I hope this can help others struggling with something similar to this.

the image is stored as NSData in user defaults and you try to instantiate an UIImage directly... maybe that is the problem — Volker, Jan 09 '15 at 11:10
Indeed, that solved the issue and the "image created" gets printed. But how do I convert the NSData to a UIImage then? @Volker — martin, Jan 09 '15 at 11:16
http://stackoverflow.com/questions/257400/nsdata-and-uiimage should cover that — Volker, Jan 09 '15 at 11:25

score 8 · Answer 1 · edited Jun 20 '20 at 09:12

Swift 3

Hey, try this beautiful code here:

Convert your UIImage to Data.

PNG:

  yourDataImagePNG = UIImagePNGRepresentation(yourUIImageHere)

JPEG :

 yourDataImageJPG = UIImage(data: yourUIImageHere,scale:1.0)

Save in UserDefaults.

    UserDefaults().set(yourDataImagePNG, forKey: "image")

Recover from:

    UserDefaults.standard.object(forKey: "image") as! Data

I hope to help!

score 0 · Answer 2 · answered Jan 09 '15 at 10:55

0

It seems like you do not call defaults.synchronize() so it's not written to the defaults file.

answered Jan 09 '15 at 10:55

qwerty_so

35,448
8
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In the saveImage-function, you mean? – martin Jan 09 '15 at 10:56
3

There is no need to call synchronize, see this answer: http://stackoverflow.com/a/9647965/267892 – Emil Jan 09 '15 at 11:21
Ok. I missed that. Also I'm not so iOS focused. In OSX it has become habit to use synchronize. I'll check the docu for updates though. Thanks for the pointer. - P.S. applies also for OS X – qwerty_so Jan 09 '15 at 11:45

Swift - saving and retrieving images from userDefaults

2 Answers2