My printer is connected to my WiFi, so is my iPhone... Still can't find the air printer...

No sure how this question relates to an AirPort Express, AirPort Extreme or Time Capsule. The printer and iPhone are both connected to the wireless network, correct?

If you cannot find the AirPrint printer from the iPhone, you might want to post in the iPhone support area to ask about this, as you will likely get a faster and more informed answer over there.

Using iPhone

If you have a question about an AirPort Express, AirPort Extreme or Time Capsule, we can likely help on that. Please re-post.

Try restarting your AirPort Extreme, Express, or Time Capsule, whichever one you have. Unplug it and let it rest for a moment, then plug it back in, wait another moment or two for it to boot, and try printing from your iPhone again.