iOS: Switching between button overlays on top of Google Maps -

this first time working xcode, , having lot of issues trying figure out how things, ui related.

currently having 3 issues:

1. i have 2 buttons, , want them both half width of screen, can't work (i want show picture, new stackoverflow, , don't have enough reputation).
2. i want buttons on top of google map, , of now, buttons aren't visible when run application (i'm thinking map on top of them, maybe).
3. when click 1 of buttons, want different set of buttons replace former ones. e.g. click button "start game", , new set of buttons "easy", "normal", , "hard" show up.

i hope can understand mean. appreciated. thank you!

for first question answer use uisegmented control. check out link uisegemnted control tutorial

2) put mapview below segmented control , adjust size of it.

3) third answer there many option. can use alert view or make custom view , put 3 buttons on , hide view. on click of start game unhidden view.