I'll piggy back off of this and shamelessly plug my mind-mapping outliner app, Mindscope for iOS, for anyone on iPad or iPhone wanting to outline and collect everything without losing the forest for the trees since you simply "zoom" into the level of detail you need.

Have heard from quite a few writers that use and love Mindscope.

https://itunes.apple.com/us/app/mindscope-thought-organizer/...