Can't say about Mac (I dont have one)
iOS has two different bar-repeat signs.
Single slash (repeat one bar) placed in the 2nd space in a 4-space measure so it appears in the center of the bar.
Double slash (repeat two bars) placed in the 4th space in a 4-space measure so it appears on the line between bars. What's With You - Mose Allison )BOB
On OSX, type % for the single-bar repeat symbol, lower case x for double-bar repeat symbol. Or, you can mouse-click on the desired symbol in the Editor box.