BE SURE TO UNINSTALL ANY VERSION OF RETROARCH YOU CURRENTLY HAVE
1a) stable (v188.8.131.52 – v184.108.40.206): Go here. Choose the version of RetroArch you want (I reccomend the latest, v220.127.116.11 at the time of writing this).
1b) nightly (v1.1+): Go here. Choose the version of RetroArch you want (I can't make a recommendation, since nightly builds are pretty random in how stable there are and how many bugs there are). You will also need to download a set of cores. Click on a core folder, and download the cores you want to use.
2) Extract RetroArch using iFile/Filza/etc.. This might take a while.
3) You should have extracted a "RetroArch.app" folder. Move this entire folder to /Applications.
5) nightly only: Take the core(s) you downloaded and move them to somewhere you can remember (I recommend making a folder called "cores" in the RetroArch.app folder, and placing them there).
Q: 我用緊18.104.22.168 版 retroarch 唔知點解global 手掣config 唔識save....有無人知咩事？我部是ipad air ios 8