If anyone (else) is coming across this issue with their custom UITextInput control. The following work around will work (assuming you don't need autocorrect): var autocorrectionType: UITextAutocorrectionType { get { .no } set { fatalError() } }

If I were to guess, I believe this is related to OS_ACTIVITY_MODE = disable, where some /n's are bleeding through.

Actually, nevermind... I turned OS_ACTIVITY_MODE on and there were still excess /n's without any OS_ACTIVITY_MODE spam in between.