Apple apps have just as much access to data on your iOS device as on any other device, the only real difference is that since iOS6 you can go into the settings on an iOS device and disable the access that the apps have to SMS's and contact lists etc. Tho this is not something the majority of iOS users are aware of.
http://ipod.about.com/od/UsingiOS6/s...ngs-In-Ios.htm
This was also possible, briefly, with Android 4.3, in 'App Ops'
Google revoked user access to 'App Ops' in 4.4.2 and now there's a bit of a furore on. Hopefully(but not likely) Google will buckle and return the 'feature'.
The only real option for droid users in the meantime is to 'root' the device.
http://www.howtogeek.com/177915/how-...android-4.4.2/
Having said all that, Sky Safari's permissions list for android contains nothing alarming, they're not accessing the phone, reading contact lists, reading SMS's or anything dodgy like that, it all appears above board.