Better way to get paths to system directories in iOS 16

In iOS, we have many directories that our app can access, e.g., document directory and cache directory.

Before iOS 16, we can get the URL to these directories with the help of FileManager.

Here is an example of how we get a URL to document directory, a folder where we can keep your app's data.

You might have seen either of these two variations.

// 1
let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
let documentsDirectory = paths.first

// 2
let documentsDirectory = try? FileManager.default.url(
    for: .documentDirectory,
    in: .userDomainMask,
    appropriateFor: nil,
    create: false)

The problems of getting path with FileManager

Both file manager's methods above have the same problems.

They are prone to error and verbose.

You have to specified both

• directory: FileManager.SearchPathDirectory and
• domain: FileManager.SearchPathDomainMask for the path you are looking for.

And if a combination of those two doesn't possible.

• An error will be thrown for url(for:in:appropriateFor:create:) method.
• An empty array will returned for urls(for:in:) method.

The following example would return nil URL.

let invalidCombination = FileManager.default.urls(
        for: .desktopDirectory,
        in: .networkDomainMask).first
// nil
    
let invalidCombination = try? FileManager.default.url(
    for: .desktopDirectory,
    in: .networkDomainMask,
    appropriateFor: nil,
    create: false)
// nil

Those two methods allow us to reach a wide range of URLs which might be beneficial for a system with more flexible, e.g., macOS.

But in iOS, everything is more restricted. Most of the time, you don't want that flexibility.

You want an easy and concise way to reference subset of paths, e.g., user's document directory, user's cache directory. And that is made possible in iOS 16.

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Getting a system directory path in iOS 16

In iOS 16, URL got a whole pack of type properties that reference a different path within a user domain.

• static var applicationDirectory: URL
• static var applicationSupportDirectory: URL
• static var cachesDirectory: URL
• static var desktopDirectory: URL
• static var documentsDirectory: URL
• static var downloadsDirectory: URL
• static var homeDirectory: URL
• static var libraryDirectory: URL
• static var moviesDirectory: URL
• static var musicDirectory: URL
• static var picturesDirectory: URL
• static var sharedPublicDirectory: URL
• static var temporaryDirectory: URL
• static var transferRepresentation: TransferRepresentation
• static var trashDirectory: URL
• static var userDirectory: URL

They are convenient properties that get the same result as the existing method, but I think it convey a clearer intention and are also easy to remember and use.

You get it right away what the code is trying to do.

let documentsDirectory = URL.documentsDirectory

// Compare to this
let documentsDirectory = try? FileManager.default.url(
    for: .documentDirectory,
    in: .userDomainMask,
    appropriateFor: nil,
    create: false)

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Conclusion

The way that we retrieve URLs to various user paths before iOS 16 isn't straightforward. The syntax is verbose and error-prone.

It can confuse newcomers, and hard to get it right, even for experienced ones.

I think these new type properties are a nice improvement to the system.