With Over you can place text over a photo. The app has several free fonts, but it also allows you to import your own font to the app.
Over was recently one of the apps offered by Apple for free as part of its celebration of the App Store's fifth anniversary.
The simple app helps add some creativity to photos by overlaying text or artwork onto your personal photos. You're able to customize your artwork by changing the color and fonts used. Built into the app is a long list of free fonts, along with many more fonts you can purchase in-app.
Recently added to the app was the ability to import any font you currently own in. All you'll need is the TTF or OTF file for the font (the app can't open a ZIP file).
Once you have the file and are sure you have the rights to use it as you see fit, you can get it to your device by e-mailing it to yourself, or via Dropbox.
I downloaded Google's Roboto font, which is coincidentally available as a purchased font from Over for 99 cents, and placed it in a Dropbox folder.
Using Dropbox to access the font files, you'll receive an error message stating Dropbox can't view the file. That's OK, just tap on the download icon in the lower-right corner of the screen and you'll be presented with the option to open it in Over.
When e-mailing a font file to yourself, you simply need to wait for it to download and then tap on the attachment. From there you'll be able to open the font in Over.
Once the import process is complete, Over will alert you and you'll then see the font listed at the top of the font list. You can now use it as you would any other font within the app.
Currently there's no method to delete installed fonts, but the Over team has indicated it's in the works and will be coming in a future updated.