I use ProCam 4 to shoot RAW.
ProCam 4 - Manual Camera + RAW by Samer Azzam
ProCam 4 - Manual Camera + RAW on the App Store
This app lets u shoot RAW, RAW+JPEG embedded, or also (JPEG 80, 90, 100) or HQ Tiff images, HDR, and is very flexible. It's a paid app but is well worth the money in my...