Although some of the answers above are correct, I have written a detailed visual tutorial for people still having problems with fonts.
The solutions above which tell you to add the font to the plist and use
[self.labelOutlet setFont:[UIFont fontWithName:@"Sathu" size:10]];
are the correct ones. Please do now use any other hackish way. If you are still facing problems with finding font names and adding them, here is the tutorial -