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You may be part of the majority of Americans who don't use the "f word" in daily life.

But the rest of us use profanity to emphasize what we're saying and typing, and we get annoyed when our "ducking" phone autocorrects the swear word into something we didn't mean to type.

According to Ken Kocienda, the former Apple designer who first developed the iPhone keyboard before it came out, it was a tradeoff they had to make.

"We decided to err on the side of not inserting obscenities into the text that might be going to your grandma," Kocienda said in an interview with Business Insider.

The key to the iPhone's keyboard is its autocorrection function. The keyboard is a bunch of buttons on a tiny touchscreen, and it relies on the iPhone being able to guess what you actually meant to type— that was the breakthrough that enabled Apple to be confident that its new phone wouldn't be hobbled by its lack of a physical, BlackBerry-style keyboard.

But sometimes guessing what word you were trying to type is tricky, Kocienda explained.

"The fact is when you actually type the dirty word, maybe you were trying to type the name of the aquatic fowl. How do you know? Because the keys are right next to each other," he explained. "So you have to make a judgment call, and we did. We had discussions about how should this software behave. It's hard. These decisions are sometimes on the knife's edge."

In fact, before the iPhone was released, Kocienda had to research really bad words — the kind you never want to say, ever — to make sure they could never accidentally pop-up due to an autocorrect fail.

"We discovered that we needed to add words that you would never say in polite speech — racial, ethnic slurs. We actually needed to research and get a compendium of these words and add them to the [iPhone] dictionary," Kocienda said.

"Seems like an odd exercise, but those words were in the dictionary, marked specially so that they would never be offered as a correction, so that the software would never assist you in typing these words," he continued.

Kocienda has recently written a book, "Creative Selection," about his insider's view of how Apple engineering works and what it was like to play a part in developing the iPhone and iPad before they were released.

You can read our entire interview with Kocienda here. You can also read an excerpt from his book here.