I've been looking at a variety of Application Extension ideas, both the extension point and what API's I'd like to integrate.

我一直在研究各种应用程序扩展的想法，既有扩展点，也有我想集成的API。

The older legacy docs in the archive are actually still pretty heavily linked by the modern Apple docs, and it says:

档案中较老的遗留文档实际上仍然与现代的苹果文档有很大的联系，它说：

Use any API marked in header files with the NS_EXTENSION_UNAVAILABLE macro, or similar unavailability macro, or any API in an unavailable framework ¹

Searching, I saw some conversations about how Swift's available attribute, and the argument iOSApplicationExtension might be the replacement.

在搜索中，我看到了一些关于SWIFT的Available属性和参数iOSApplicationExtension可能会被替代的对话。

https://docs.swift.org/swift-book/documentation/the-swift-programming-language/attributes/#available

Https://docs.swift.org/swift-book/documentation/the-swift-programming-language/attributes/#available

Can someone comment/clarify?
Also, if this is true, is there some way of asking Xcode to tell me what API's are iOSApplicationExtension ?

有谁能发表意见/澄清一下吗？另外，如果这是真的，有没有办法让Xcode告诉我iOSApplicationExtension是什么API？