Method to retrieve a list of downloadable fonts on iOS 7. This method may block for a while (it can involve a network call) so don't call on main thread. The return is a dictionary that maps font families to arrays of font names in that family.

gistfile1.txt

+ (NSDictionary *)downloadableFonts
{
    CTFontDescriptorRef desc = CTFontDescriptorCreateWithAttributes((CFDictionaryRef)@{(id)kCTFontDownloadableAttribute : (id)kCFBooleanTrue});
  CFArrayRef matchedDescs = CTFontDescriptorCreateMatchingFontDescriptors(desc, NULL);
    NSArray *array = (__bridge NSArray *)matchedDescs;
    
    NSMutableDictionary *families = [NSMutableDictionary dictionary];

    for (UIFontDescriptor *fontDescriptor in array) {
        NSString *familyName = fontDescriptor.fontAttributes[UIFontDescriptorFamilyAttribute];
        NSString *displayName = fontDescriptor.fontAttributes[UIFontDescriptorVisibleNameAttribute];
        NSString *postscriptName = fontDescriptor.postscriptName;

        NSMutableDictionary *family = families[familyName];
        if (family == nil) {
            family = [NSMutableDictionary dictionary];
            family[@"name"] = familyName;
            family[@"fonts"] = [NSMutableArray array];
            families[familyName] = family;
        }
        
        NSMutableDictionary *fontDict = [NSMutableDictionary dictionary];
        fontDict[@"displayName"] = displayName;
        fontDict[@"postscriptName"] = postscriptName;
        fontDict[@"descriptor"] = fontDescriptor;
        
        NSArray *languages = fontDescriptor.fontAttributes[@"NSCTFontDesignLanguagesAttribute"];
        fontDict[@"languages"] = [languages componentsJoinedByString:@", "];
        
        NSMutableArray *fonts = family[@"fonts"];
        [fonts addObject:fontDict];
    }
    
    return families;
}