Debug UIEvent

Application.swift

  override func sendEvent(_ event: UIEvent) {
      NSLog("sendEvent \(event)")
      super.sendEvent(event)
      var vc = keyWindow!.rootViewController!
      while vc.presentedViewController != nil {
          vc = vc.presentedViewController!
      }
      
      // Find hit view
      if let view = vc.view {
          if let t = event.allTouches?.first {
              let p = t.location(in: view)

              if let hitView = view.hitTest(p, with: event) {
                  NSLog("hit view = \(hitView)")
              }
          }

      }
}

Then debug view hierarchy in Xcode, filter view using the memory address of the hit view.