What you need to build for Apple platforms.
WHAT IS MANDATORY
Apple hardware running macOS The development environment, which runs only on macOS
WHY THAT IS ABSOLUTE
Building and signing applications requires tooling Apple provides only for its own system.
WHAT THAT MEANS PRACTICALLY
There is no supported route to building iOS applications on Windows or Linux.
WHAT THE PARTIAL ALTERNATIVES ARE
Cloud-hosted build services running macOS Cross-platform frameworks that still require macOS for the final build and submission
WHAT NONE OF THEM REMOVE
The requirement for macOS somewhere in the process.
WHAT ELSE YOU NEED
A developer account, free for local development A paid membership for device testing beyond limits, and for distribution
WHAT THE FREE ACCOUNT ALLOWS
Building and running on your own device, with certificates that expire quickly.
WHAT THE PAID MEMBERSHIP ALLOWS
Distribution, testing distribution, and access to certain capabilities.
WHAT TO BUDGET FOR
Hardware, the annual membership, and test devices.
WHAT TO ESTABLISH BEFORE COMMITTING TO A PROJECT
Whether that cost is justified by the audience.