プロトコルエクステンションのinitでクラスのselfを置き換える手法を使うことで、swift-corelibs-foundationのNSNumberをCFNumberCreate()で作成する様に変更するPRを書いた。 https://github.com/apple/swift-corelibs-foundation/pull/1093 (edited)

Use CFNumberCreate() as factory initializer on NSNumber by norio-nomura · Pull Request #1093 · apple/swift-corelibs-foundation

This replaces #1025 by further utilizing the Factory Initializer Method (SR-5255). Use CFNumberCreate() as factory initializer on NSNumber Remove NSNumber._objCType Change the properties of NSNu...