This app can convet the longitude,latitude to GeoHex v3 code and draw the hex where you dragged by your finger.
But I'm a beginner in objective-c and this is the first time I use github, so there may be not so good parts, so please let me know when you find something wrong.
And I couldn't find the way how to test the code by reading text file per line using for loop, so I just tested some patterns manually. I will continuously invest how to do it , and want to add the test code. If you know how to do it or have clues, please let me know.
By the way, I applied this app to Apple, the response was not only reject, but also ,the message that with such a little function you should do it on browser using HTML5 or ad hoc version... lol. I'll effort more.