NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

How to use #available to check for API availability

Swift version: 5.2

Paul Hudson    @twostraws   

One of my favorite Xcode features is the ability to have Xcode automatically check API availability for you, which means it will refuse to run code that is not available on the minimum iOS version you support.

Of course, there are times when you really do need to use a newer feature, for example if you want to use UIStackView where it's available but otherwise show a message to users asking them to upgrade. For this, Swift has #available, which lets you state that a certain block of code should only execute on specific versions of iOS.

To use the previous example, this code checks whether the user has iOS 9.0 or later on their device:

if #available(iOS 9, *) {
    // use UIStackView
} else {
    // show sad face emoji
}

Any code inside the // use UIStackView block can be executed as if your deployment target were iOS 9.0.

If you want, you can mark whole functions or classes as requiring a specific iOS version by using @available, like this:

@available(iOS 9, *)
func useStackView() {
    // use UIStackView
}
Hacking with Swift is sponsored by NSSpain

SPONSORED Announcing NSSpain 2020: Remote Edition! An online, continuous conference for iOS developers. We’ll start on Thursday and finish on Friday, with talks, activities, and lots of fun for 36 hours, non-stop. Sound good? Join us!

Find out more

Sponsor Hacking with Swift and reach the world's largest Swift community!

Available from iOS 7.0

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 3.0/5

Link copied to your pasteboard.