Apple announced in June 2016 that it would force all iOS app developers to use HTTPS starting with 2017. Only about 3% of 200 enterprise iOS apps were updated to use encryption. Apple tried to force iOS developers through the WWDC announcement, but very few updated their apps to support encrypted communications. Apple has all but given up on enforcing ATS, being in danger of killing its app ecosystem. For the time being and the foreseeable future, ATS will remain an optional security measure in iOS, despite its palpable advantages.
Source: https://www.bleepingcomputer.com/news/apple/apple-gets-lazy-on-encryption-extends-https-enforcement-deadline-for-ios-apps-indefinitely/