Hey there,
So first off, I'm going to explain that I love mobile development. iPhone, Android, Windows, you name it I love coding it. It's a lot of fun to work with and a lot of fun to get excited over. Text based apps are really easy, getting the input, having it display as you type and sending the information to another phone with an id registered to a pre-existing phone number isn't all too bad either.
Usually, apps I tackle are much more expensive and take months; however, I figured a nice break from that would be nice. I've worked with sending information between phones multiple times for my own enjoyment and can send information via sms, mms, bluetooth, and email from a smart phone and it is really just things I've done in the past. Mostly I have done this stuff on Android; however, I have dabbled a bit into iOS for it.
I'm confident I could do this, have it tested and working before 10 days is up, and that's why I've put the date that I could get it to you within 10 days. Since you've shared a link to a similar app that also has source code, I could probably get exactly what you want in a much shorter time have it tested and can send it to you for approval. Of course as is most things, this will be a back and forth experience with a lot of communication so that I can get you exactly what you're looking for.
If you're still searching through all the bids, please don't hesitate to send me a message if you want more elaboration on what I have done. Cheers, and thanks.