I've developed a personality quiz app here entirely in code. Some of the separators keep disappearing though - it's not consistent from question to question, but it's usually one or two in the middle.
I can update with code, but I'm not sure what aspect of TableView's code is causing this problem.
Are you take the screen shot from the simulator ? if it's from simulator, it's normal, as the mac book don't have enough pixel to display the separator. change your simulator to iPhone 8 would be fine.