What's the Swift equivalent of Objective-C's "#ifdef __IPHONE_11_0"?

Question

I want to use Xcode 9 to add iOS 11 code to my project while keeping the option to compile the project with Xcode 8 which only supports iOS 10.

In Objective-C I can do this by using a preprocessor directive to check if __IPHONE_11_0 is defined. Which will hide the code if I'm compiling with a Base SDK earlier than iOS 11. Like this:

#ifdef __IPHONE_11_0
    if (@available(iOS 11.0, *)) {
        self.navigationController.navigationBar.prefersLargeTitles = YES;
    }
#endif

Is there a way to do that in Swift?

if #available(iOS 11.0, *) doesn't work because that's a runtime check.

Answer 1

The iOS 11 SDK comes with Swift 3.2 (or Swift 4), so you can use a Swift version check to accomplish the same thing:

#if swift(>=3.2)
    if #available(iOS 11.0, *) {
        …
    }
#endif

Answer 2

This is the solution suggested by Apple:

if #available(iOS 11.0, *) {
    // iOS 11 specific stuff here
} else {
    // non iOS 11 stuff here
}

Please refer to this resource (watch video on mark 6:50 for more details)

Answer 3

If you want to put the condition outside of the function, you could do it like below.

@available(iOS 11.0, *)
func functionName() {
 // function contents
}