CODEWITHSUNDEEP
iosswift2
Travis M.
Travis M.

Reputation: 11257

Delete File After contentsOfFile Load

I am loading an array of UIImage from the iOS Documents directory:

var images = [UIImage]()
for fileName in fileNames {
    images.append(UIImage(contentsOfFile: "\(imagesPath)/\(fileName).png")!)
}

I'm going to continue using this array but I don't need the files anymore, so I go ahead and delete them:

for fileName in fileNames {
    do {
        try NSFileManager.defaultManager().removeItemAtPath("\(imagesPath)/\(fileName).png")
    } catch {
        print("Error")
    }
}

When I do this, my array of UIImage is now invalid and gives me errors while trying to access them. Shouldn't this be in memory and not related to the files on disk?

I tried using the ".copy()" command on the images when I load them but that made no difference.

I have confirmed that the delete is the issue above because if I comment out that line the app works great with no errors. I only get errors accessing the array after I delete the files from disk.

Is there a way to sever this connection?

Edit: Per the correct answer from @Wain, the code works fine if I change it to:

var images = [UIImage]()
for fileName in fileNames {
    let imgData = NSFileManager.defaultManager().contentsAtPath("\(imagesPath)/\(fileName).png")!
    images.append(UIImage(data: imgData)!)
}

Doing this doesn't keep the link back to the file on disk.

Upvotes: 2

Views: 244

Answers (1)

Wain
Wain

Reputation: 119031

The images haven't been displayed so the data hasn't fully been loaded yet, only enough to know the image details and size has been loaded. This is for memory efficiency. depending on the image format and usage different parts of data may be loaded at multiple different times.

If you load the file into NSData, ensuring that it isn't memory mapped, and create the image from that then the data and image should be unlinked from the underlying file. This is less memory efficient and it would be better to keep your current code and delete the files when you know you're finished with the images all together.

Upvotes: 3

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