Chapter 16: Bronze Challenge

iOS Programming: The Big Nerd Ranch Guide (6th Edi 16. Saving, Loading, and Application States
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This was pretty simple all that needed to be done was to change the data representation to use UIImagePNGRepresentation(_:) instead of UIImageJPEGRepresentation(_:_:). The change is made in the setImage(_:forKey:)` method.

ImageStore.swift - before

class ImageStore {
    ...
    func setImage(_ image: UIImage, forKey key: String) {
        cache.setObject(image, forKey: key as NSString)
        
        let url = imageURL(forKey: key)
        if let data = UIImageJPEGRepresentation(image, 0.5) {
            let _ = try? data.write(to: url, options: [.atomic])
        }
    }
    ...
}

ImageStore.swift - after

class ImageStore {
    ...
    func setImage(_ image: UIImage, forKey key: String) {
        cache.setObject(image, forKey: key as NSString)
        
        let url = imageURL(forKey: key)
        if let data = UIImagePNGRepresentation(image) {
            let _ = try? data.write(to: url, options: [.atomic])
        }
    }
    ...
}