First at https://duck.co/help/mobile/ios
it has a list of browsers, this list is missing the Phlo browser (https://itunes.apple.com/us/app/phlo-qui...
Under safari on the iOS page it says Adding DuckDuckGo to Safari (No Jailbreak required)(Only works on network it was set up on) but on the safari page it page it only says DuckDuckGo is not available in Safari on iOS but you can get our iOS app here.
On the android page it has a list of browsers that work with DuckDuckGo, it has the browser next to most of the names. Some of these browsers have iOS versions but under iOS it does say browser.An example of this Dolphin Browser.
Also the list of browsers excludes mercury browser which has DuckDuckGo support (http://mercury-browser.com