iOS Programming, 6th Ed., Ch 19 - UIGuestureRecognizer

There may be a bad bug in Xcode 8.3.3 that is happening when compiling the exercise in Chapter 19 (Pg345 finishes it).
I was unable to get the program to run although there were no errors.
I compared my code to that of the solution, which did run, and rearranged all my code to flow in the same order as the solution code was given.
It still did not run. Then I started changing the exact syntax of statements to match the solution code.
I was lucky, the first statement I changed was the long statement (in my code) that in the solution in the book was shortened by using two lines.
When it compiled, everything worked perfectly. Go figure!
Anyway, here is the difference between working and not working.

Chapter 19 UIGestureRecognizer and UIMenuController

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith
OtherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true

Doesn’t work

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer,shouldRecognizeSimultaneouslyWithOtherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true

Not sure what kind of book/eBook you have, but the one I’m reading separates the argument label shouldRecognizeSimultaneouslyWith from the parameter name otherGestureRecognizer (also note the lowercase ‘o’ as is the convention for method names).

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer,
    otherGestureRecognizer: UIGestureRecognizer) -> Bool {
  return true

Apple Developer Documentation: gestureRecognizer(_:shouldRecognizeSimultaneouslyWith:)

You are right, it is an argument label + parameter and not one long run together ver-long single parameter name as I had thought. The change in capitalization is key to recognizing it that I had overlooked. Good catch. But, boy this took me a lot of time to find!