Exploring the Swift @available Attribute: What You Need to Know

The @available attribute in Swift is a powerful feature that ensures your code works seamlessly across different platforms and versions. Whether you are supporting older iOS versions or leveraging new APIs, understanding this attribute is crucial for robust and future-proof app development.

This blog walks you through Swift @available usage, syntax, and best practices while showing how to write code that gracefully adapts to multiple platforms.

What is the @available Attribute in Swift?

The @available attribute allows you to specify the platform availability of a particular method, function, or class. By using this attribute, you can indicate whether a piece of Swift code is available on a specific platform version or if it has been deprecated.

Key Features of the @available Attribute

• Helps manage platform availability.

• Prevents compiler errors when using new APIs on unsupported platforms.

• Simplifies availability checks for ios versions and other platforms.

• Enhances app maintainability when targeting older versions and newer features simultaneously.

Why is @available Important for App Development?

In Swift, apps often need to run code on multiple platforms and ios versions. The @available attribute ensures your app respects the minimum deployment target, avoiding crashes and deprecation warnings. Moreover, it helps developers adapt to the latest Swift version, manage api availability, and reduce compiler errors during development.

How to Use the @available Attribute in Swift

The @available attribute can be applied to various declarations like functions, methods, classes, or variables. Here's the syntax:

Swift

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1@available(platformName version, ...)

Example: Targeting a Specific iOS Version

If a method was introduced in iOS 14, you can use the following:

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1@available(iOS 14.0, *)
2func useNewFeature() {
3    // Code that uses a new API available in iOS 14
4}

Here:

• iOS 14.0 indicates the first version where this function is available.

• * denotes other platforms are unaffected.

Specifying Multiple Platforms

You can make your Swift code compatible with multiple platforms by listing them:

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1@available(iOS 13.0, macOS 10.15, *)
2func universalFeature() {
3    // Code for both iOS and macOS
4}

This ensures your app works across platform names like macOS and iOS.

Using Availability Checks

When you need to execute certain code only on supported platform versions, availability checks help:

Example: Checking Availability at Runtime

Use #available to verify platform availability dynamically:

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1if #available(iOS 14, *) {
2    useNewFeature()
3} else {
4    // Fallback code for older iOS versions
5}

This approach is useful for supporting older iOS versions without sacrificing new features.

Practical Scenarios for @available

1. Managing Deprecation Warnings

When an API is deprecated, you can handle it gracefully:

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1@available(iOS, deprecated: 15.0, message: "Use updatedFunction instead.")
2func deprecatedFunction() {
3    // Code that is no longer recommended
4}

This provides a note to developers and ensures the compiler issues a warning when the method is used.

2. Supporting Multiple Platforms with macOS and Mac Catalyst

With the rise of Mac Catalyst, your app might need features for both macOS and iOS:

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1@available(macCatalyst 14.0, *)
2func macCatalystFeature() {
3    // Code exclusive to Mac Catalyst
4}

This makes it easy to write code that adapts to newer versions of macOS and iOS.

Best Practices for Using @available

1. Set the Minimum Deployment Target Correctly

Always align your usage of @available with your app’s deployment target to avoid unnecessary compiler errors.

2. Use Fallbacks for Older iOS Versions

When targeting older versions, provide alternative implementations to maintain functionality.

3. Test Thoroughly Across Platforms

Regularly test your app on all target platforms to ensure smooth behavior and compatibility.

4. Document Availability Information

Use clear declaration messages to inform other developers about version-specific behavior.

Advanced Usage of @available

Combine with Objective-C

When working with Objective-C code or third-party frameworks, the @available attribute helps ensure compatibility:

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1@available(iOS 12.0, *)
2@objc func compatibleWithObjC() {
3    // Code callable from Objective-C
4}

Platform-Specific Features

Leverage availability checks for platform-specific functionality:

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1@available(tvOS, unavailable)
2func notForTvOS() {
3    // Code excluded from tvOS
4}

This ensures your Swift code won’t trigger compiler errors for unsupported platforms.

Final Thoughts on @available in Swift

The @available attribute in Swift is an indispensable tool for modern app development. By mastering it, you can efficiently manage platform availability, support older versions, and incorporate new APIs into your projects. Whether you are adapting to new iOS versions, maintaining cross-platform compatibility, or avoiding deprecation warnings, this feature is your go-to solution.

As you write code for multiple platforms, remember that clear availability checks and thoughtful usage of the @available attribute will keep your app running smoothly and future-proof.