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Marking API Availability in Objective-C

 1 year ago
source link: https://developer.apple.com/documentation/swift/marking-api-availability-in-objective-c
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Marking API Availability in Objective-C

Use a macro to denote the availability of an Objective-C API.

Overview

In Swift, you use the @available attribute to control whether a declaration is available to use when building an app for a particular target platform. Similarly, you use the availability condition #available to execute code conditionally based on required platform and version conditions. Both kinds of availability specifier are also available in Objective-C.

For detailed information about specifying platform availability, see Declaration Attributes in The Swift Programming Language.

Mark Availability

Use the API_AVAILABLE macro to add availability information in Objective-C:


@interface MyViewController : UIViewController
- (void) newMethod API_AVAILABLE(ios(11), macosx(10.13));
@end

This is equivalent to using the @available attribute on a declaration in Swift:


@available(iOS 11, macOS 10.13, *)
func newMethod() {
    // Use iOS 11 APIs.
}

Check Availability

Use the @available() keyword to check availability information in a conditional statement in Objective-C:


if (@available(iOS 11, *)) {
    // Use iOS 11 APIs.
} else {
    // Alternative code for earlier versions of iOS.
}

This is equivalent to the following conditional in Swift:


if #available(iOS 11, *) {
    // Use iOS 11 APIs.
} else {
    // Alternative code for earlier versions of iOS.
}

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