First, Apple's signature.
Generally speaking, you need an enterprise developer account to provide an enterprise certificate. The tutorial is as follows.
How to install ipa files on Apple phones? Apple enterprise signature solution!
Second, TF signature.
As one of the most stable signature methods at present, TF signature itself is widely recognized by developers, and TF signature is much easier than the review of App Store. The tutorial is as follows.
How to install ipa file on Apple mobile phone with TF signature
The above is the whole process of how Apple signed and TF signed to install ipa files on Apple phones. In fact, the whole process of installing ipa files is very convenient and can be operated on mobile phones. I hope it helps you.