Swift: Cache int from disk

Question

For preferences set by users, I sometimes have to read values from disk. In order to avoid unnecessary (slow) disk reads, I cache these values so if the app accesses them often, it will only be memory access, not a storage access.

Here is an example for what I have been doing about this for almost a decade now:

let DEFAULT_COLUMN_COUNT = 4

var columnCount = -1

func getcolumnCount() -> Int {
    
    if(columnCount != -1) {
        return columnCount
    } else if let count = UserDefaults.standard.object(forKey: "COLUMN_COUNT") as? Int {
        columnCount = count
    } else {
        columnCount = DEFAULT_COLUMN_COUNT
    }
    return columnCount
}

I have been writing the same kind of algorithms more or less for years but at this point I'm sure there must be a smarter way to handle this.

I have thought about writing a small wrapper that lets me pass a default value and the UserDefaults identifier but I first wanted to make sure whether there is already something like this included in the Swift language/ if there is a small project for this on GitHub or if my approach is completely wrong in all regards - of course it depends on the specific use case but generally this has worked for me quite well in terms of performance

Answer 1

From Apple developer docs:

UserDefaults caches the information to avoid having to open the user’s defaults database each time you need a default value. When you set a default value, it’s changed synchronously within your process, and asynchronously to persistent storage and other processes.

So, it looks like you should not worry about "unnecessary (slow) disk reads".