Buoyed by the success of getting app #1 approved, I decided to go with another fairly utilitarian app. Quadratic functions are so fully understood that it explains why there are so many apps for them! I knew my app would have to differentiate itself from what was already out there, and I chose to do that by producing results in exact form, that is, in terms of integers and fractions and radicals, rather than opting for the quick and easy decimal results. After all, I anticipated a math student using it to check his or her work, and they’re not going to get their results in decimal form if they’re doing it by hand.
With the development of Quadratix I also wanted to learn some new coding skills. The first was the tab bar, but like the flipside view, it was all in Xcode so there really wasn’t anything to learn except how to make graphics for the tab bar, and more importantly, how to get one view to share its data with another. That was actually a fairly complicated task, but once again, I found someone on iPhoneDevSDK who did the whole thing. I invested a lot of time in finding and implementing this solution, but I know it was worth it in case I ever need to do it again.
The next skill I learned was graphing. Also a good skill to have for math-related apps! Installing and implementing Core Plot took a lot of time and a lot of research, but again the information was readily available and it was more a matter of making sense of what I was doing. So now I had a nifty app that does algebra in one view and a graph in the other.
Finishing touches included a segmented control (easy!) and better graphics than app #1 had. I discovered the gradient tool in Photoshop and had a lot of fun with that for the backgrounds. The logo I did in Microsoft Word with Word Art, and then save the file as a web page to get the logo as a png. The decision to add an iAd banner came towards the end, as I had always anticipated selling my app for 99¢.
How I came to decide to make the app free is that, first, I asked my daughter’s opinion and she said it should be free. I didn’t agree right away. Then I heard a great speech by Theo Gray of Wolfram about how his coffee table book The Elements came to be an iPad app, and if his amazing app is only $13.99 then there was no way I could ever charge anything for my app. So I made some room and added an iAd. It was the right thing to do.
All in all, I’m pretty pleased with how it came out. I did forget one big thing: when I submitted the app I forgot to enable iAds, so I missed out on any ad revenue with the initial jump in downloads. But since I make almost nothing with the ads it really didn’t make much difference. When I discovered my error about a month later I was prompted to move a lot more quickly on getting out my first update for Quadratix, which came about right after I submitted app #3. But with the update I also made a nice improvement in the coding, adding the ability to read fractions, so I think it will end up being a worthwhile update. I added that capability to Slant Asymptote Shortcut and will be submitting that update very soon, too.