Telegram’s emoji-picker edge tuck effect uses the private UIKit class _UIPortalView to create 8 live-updating views of the scrolling grid sliced into strips then progressively rotate them around the X axis to approximate a quarter-circle
In the source they skirt Apple's private API static analysis checks through simple string obfuscation:
portalViewClass = NSClassFromString([@[@"_", @"UI", @"Portal", @"View"] componentsJoinedByString:@""]);
Telegram's UIKitUtils class is chock full of crazy things like this, and they probably aren't worried about Apple's ire because they're so big that booting them off the App Store would not be in Apple's best interest