Let's face it - we love DuckDuckGo so much that we don't want the DuckDuckGo app. No. We want DuckDuckGo to be integrated into Safari.
Of course, that's never going to happen, but if you're jailbroken, this is a dream come true for you.
I am about to tell you how to add DuckDuckGo as your default Safari search engine on ANY iOS device.
Let me repeat: you need to be jailbroken to do this. If you know what a jailbreak is, full steam ahead. If not, stay back until Apple releases this officially (and then, at least we will prevail)
You will need:
A jailbroken iOS device
iFile (from Cydia, get the trial)
The same passion for DuckDuckGo as me
0) [added late] Open Settings > Safari and set Google as the default search engine. This'll change, don't worry.
1) Open iFile. Keep tapping the back thing until you end up at /
2) Find User and tap it.
3) Tap Library.
4) Find Safari and tap it.
5) Tap SearchEngines.plist and choose Property List Editor.
6) Tap SearchProviderList Array.
7) Tap 0.
8) Change ScriptingName to DuckDuckGo. To do this, tap it and type DuckDuckGo in place of Google.
9) In the same fashion, change SearchURLTemplate to
http://www.duckduckgo.com/?q={searchTerms}
10) Also change ShortName to DuckDuckGo.
11) Tap Done.
12) Go into Settings and tap Safari again. Tap Search Engine and lo and behold! DuckDuckGo has replaced Google. Tap it and press HOME.
13) If you have an iPod touch 3rd generation or above, or an iPhone 3G [S] or above, double press your HOME button and hold Safari. Tap the (-) button and restart your phone.
14) Result - DuckDuckGo should now be the default search engine. A little extra treat is that you get autocorrection of Google's search engine, but with the non-trackiness of DuckDuckGo.
Tested on an iPod touch (4th generation) with iOS 5
PLEASE TEST WITH OTHER FIRMWARE VERSIONS. I AM NOT HELD RESPONSIBLE FOR ANYTHING THAT GOES WRONG...