Solfège is a complete app for singing. It contains the following components:
SCALE
In the Play view you can play notes, basically as on a keyboard.
In the Sing view notes are shown one by one and your goal is to sing the right note before the answer is being played.
In the Listen view your goal is to name the notes which you hear.
The program starts with only small intervals (seconds and thirds). As you progress, you can adjust the maximum interval up to a full octave.
Aim for perfection. You should be able to do the exercises for a few minutes without any mistake before moving on to the next interval. Try to practice at least 10 minutes per day.
PITCH (iPhone only)
Whistle a tone and see the corresponding note on the screen. If the note is displayed in red it means you are a bit too high. Blue means a bit too low. Black means you are whistling at just the right frequency.
METRONOME
Just what you expect. Simply set the time signature and the tempo. The first beat of every measure is accentuated.
TUNING FORK
Giving you a perfect 440 Hz by tapping on the tuning fork, or shaking your iPhone.
The app contains an extensive settings screen, in which you can select the tonic (the lowest tone on the scale), the maximal interval and the delay time (the time between the question and the answer), and several ways to display the keyboard.
If you are in to music and want to practice your skills and train your musical ear (or just need to have a handy music tool with you), this is the app to use.
Enjoy!