How to check if a font is available in version of iOS?

The following example code prints a list of each font in every family on the current device:

NSArray *fontFamilies = [UIFont familyNames];

for (int i = 0; i < [fontFamilies count]; i++)
{
    NSString *fontFamily = [fontFamilies objectAtIndex:i];
    NSArray *fontNames = [UIFont fontNamesForFamilyName:[fontFamilies objectAtIndex:i]];
    NSLog (@"%@: %@", fontFamily, fontNames);
}

From: StackOverflow