Question: I was interested in creating a mapping application in the iOS environment. I have looked at what ESRI has to offer, but I am interested in open source. Could anybody suggest any documentation or point me to some place where I could start learning how to create such apps?

Thanks.

Answer: 
[see note above re: needing more detail. this is just one possible implementation].

Implement a native-*like* app with HTML5 + CSS + Javascript (yey, easy stuff, no Objective C) and then wrap it in WebView and you have an "app". Want it the easy way?

1. Take the OpenLayers mobile map sample and modify.

<http://openlayers.org/dev/examples/mobile-jq.html#mappage>
2. Use PhoneGap to build your app

<http://docs.phonegap.com/en/2.2.0/guide_getting-started_index.md.html>

3/4/5 - Take same code build and build for Blackberry, Android, Etc...
[Mapbox IOS SDK](http://mapbox.com/mobile/) is another possible option. It was forked from the [route-me](https://github.com/route-me/route-me) sdk.

Note that there are non-obvious [terms-of-service limits](http://mapbox.com/mapbox-ios-sdk/#tile_caching__class) for part of the Mapbox IOS SDK. They're not unreasonable (its just the Mapbox ToS), just something to note.