Conditionally compile based on iOS version? (previewCGImageRepresentation broke)

Using Swift
1

There are plenty of conditional compile options in Swift, but none seem to address my need:

I’ve run into an issue where Xcode 13b2 (iOS 15 SDK) changed the Swift return type of AVCapturePhoto.previewCGImageRepresentation(). In Xcode 12.5.1 (iOS 14 SDK), this method returns Unmanged<CGImage>. In 13b2 - 13b4, it returns CGImage?.

I need my code to compile under both Xcode versions, since Xcode 13 has other issues, and can’t be used to submit builds to the App Store. I thought I was clever writing this, but it won’t compile, because it’s not conditional code compilation check but rather a runtime check:

extension AVCapturePhoto {
    func stupidOSChangePreviewCGImageRepresentation() -> CGImage? {
        if #available(iOS 15, *) {
            return self.previewCGImageRepresentation()
        } else {
            return self.previewCGImageRepresentation()?.takeUnretainedValue()
        }
    }
}

Another possibility might be to create a user-defined Xcode setting, but I don’t think that can be done conditionally based on Xcode or SDK version.

There might be some unsafe pointer histrionics one can do…

Any other ideas?

2

Since both the SDK version and the compiler version are tied to an Xcode release, you can use the #if compiler directive as a stand-in for the SDK version:

import AVFoundation

extension AVCapturePhoto {
  func stupidOSChangePreviewCGImageRepresentation() -> CGImage? {
    #if compiler(>=5.5)
      // iOS 15+ SDK, macOS 12+ SDK
      return self.previewCGImageRepresentation()
    #else
      return self.previewCGImageRepresentation()?.takeUnretainedValue()
    #endif
  }
}
3 Likes
3

Ahh, thank you!

1 Like
4

I've used setValue(forKey:) for some new Xcode 13 APIs. You would use value(forKey:).