There wasn't an app for that.

So Dan Carns created one.

The Knoch High School junior taught himself to develop apps for the iPhone and now has published two, which have been downloaded from as far away as Japan and New Zealand.

One is a game and the other is an educational app called Pre Calc.

“I found it was really fun to start with nothing and end up with some sort of working software that you could manipulate and build upon,” he said.

Carns said he has always been interested in how computers work “behind the scenes.” After taking an intro to programming class at school last year, Carns said he was hooked.

It was after that class he decided he wanted to create an app. But first he needed a computer.

To create an Apple app, Carns needed a Mac system, which his family didn't own.

So he started working at a friend's farm to earn the money for his computer.

In December, Carns began developing his first app, Hot Air Classic, a game that requires its player to navigate a hot-air balloon through airspace filled with planes.

The game took Carns a month and a half to develop and took a “ton of trial and error.” He said he would work on it before school and often worked late into the night.

“Hot Air Classic was first and foremost a project that taught me the fundamentals, which I have used repeatedly in creating other apps,” he said.

Carns used the Swift language, a program language for app building that was first available in September.

The teen's second app, Pre Calc, took only a weekend.

“With Pre Calc, my aim was to simplify some of the calculations we were doing in Pre Calculus,” he said. “It is an ongoing project that I am adding to as I advance through the class.”

Carns credits Knoch teacher Michael Losk for teaching him the fundamentals of programming in other computer languages, which helped when Carns struck out on his own.

“It was also nice to see him apply computer science concepts and principles that I've taught in class into a product that he's able to publish on the Apple iTunes store for the world to enjoy and use,” Losk said.

Losk said, although he has downloaded the apps and played them and also has passed along ideas for future apps and websites that may provide extra help when developing apps, Carns gets the credit.

“Overall, what he's developed has been 100 percent his direction and vision,” he said.

His mother, Terry Carns, said she is very proud of what Dan has accomplished.

“He's been quite dedicated and persistent,” she said.

Dan Carns even went so far as to get an Apple representative on the phone to answer his mom's questions, she said.

“I knew he was pretty serious when he threw in his own money for the developer's fee,” Terry Carns said.

Terry Carns, who admits she is not tech savvy, said she had to upgrade her phone to play Dan's game.

Dan Carns said he's made a nominal amount of money for his apps and cannot expect much until he has established a presence in the online store.

Still, his apps have been downloaded in the Caribbean, Great Britain, Luxembourg, Canada, the Asian Pacific and China, as well as Japan and New Zealand.

And the teen plans to keep busy.

Carns said he has more than a dozen apps in the works. Some are games, but most are “fledgling educational/productivity apps,” he said.