Apple will reportedly use Qualcomm's 5G chips on iPhones for the next four years. This revelation comes from a document published by the United States International Trade Commission. It also states that Apple is slated to release a 5G-ready iPhone in 2020, which will be powered by a Snapdragon X55 5G modem.
https://www.notebookcheck.net/Apple-will-use-Qualcomm-s-5G-chips-on-iPhones-till-2023-according-to-report.454122.0.html