Apple has announced to developers that as of July, all app updates submitted to the App Store will need to support the iPhone X display and be built with the iOS 11 SDK. Apple has been enforcing the policy for all new app submissions since last month, following an announcement to developers earlier this year.
With the latest announcement, the policy has been extended to any app updates that developers want to submit, which will help push actively developed apps to gain support for the iPhone X Super Retina display. Developers submitting updates will also presumably need to abide by the same App Submission Guidelines requiring that they include proper iPhone X screenshots with their updates.
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