Even when WhatTheFont isolates a character it might not be sure what it is. Tap the box to the right of the image and the iPhone keyboard pops up. You can tell WhatTheFont what specific character is highlighted in the image.
In this example, the one clearly recognized characters are the hyphen and the B. For many fonts this would not be enough to make a good identification but I went ahead and tried it.
I also tried editing my photo of the text in some other iPhone apps, isolating the y and a a bit more and uploaded that example. WhatTheFont did an even better job of character recognition with that image.