It is mostly true but not necessarily true in all cases.
In order for your app to make money as a freely downloadable program that pays for itself through advertising, it needs to do a great job of getting people to use it over and over again.
Unfortunately, statistics show that most apps aren't this "sticky".
The average smartphone app gets run about 12 times.
When you break down the numbers even more, this amounts to about 80 potential viewer impressions or chances to display an advertisement.
Unfortunately, this amount simply isn't enough to pay for the app and to guarantee you a profit.
We still say this with some degree of reservation.
Some apps are incredibly sticky, and Pandora is one of them.
People log on to Pandora day in and day out, listening to music they've never heard before and being exposed to highly targeted advertising.
Pandora is free, and you can bet they're making a handsome profit from their advertisers.
Your app might be this sticky, but you don't have any way of knowing whether it is until you start selling it on the app store.
Software can be installed with your app that will gauge average usage, and that usage data will ultimately tell you whether offering your app for free is a good idea.
Get the hard data first, and then make the important decision.
We'll be here to help you with it.
Your best bet as a prospective iPhone app developer is to get in on the action while it's still hot.
Edge your way into a niche and claim dominance for as long as you can muster up the strength.