nca.swift

public extension UIView {
   // Return nearest common ancestor between two views
   public func nearestCommonAncestor(with otherView: UIView) -> UIView? {
      var mySuperviews = sequence(first: self, next: { $0.superview }).reversed().makeIterator()
      var theirSuperviews = sequence(first: otherView, next: { $0.superview }).reversed().makeIterator()
      var nca: UIView? = nil
      while let mine = mySuperviews.next(), let theirs = theirSuperviews.next(), mine === theirs {
         nca = mine
      }
      return nca
   }
}