How would this work with the .h and .m files? Do you have to convert code piece by piece?

First, of course, you can paste the contents of both .h and .m files into our code converter.
Swiftify automatically joins the interface and implementation section for classes and other declarations.

Second, you can use our File & Project converter, where you can upload multiple (zipped) .h or .m files and get them joined and converted to .swift files.

Third, you can use our Finder extension (included in Swiftify for Xcode) to conveniently convert multiple files, folders, and even projects right from your Mac!

Finally, the Advanced Project Converter (included in Swiftify for Xcode and available in the Cloud plan) is the most convenient way to gradually convert your project to Swift.