A simple Objective-C method that will register all of the TTF font files in your application with Core Text.

RegisterFonts.m

+ (void)registerFonts {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        NSArray * paths = [[NSBundle mainBundle] pathsForResourcesOfType:@"ttf" inDirectory:@""];
        for (NSString * path in paths) {
            NSURL * url = [NSURL fileURLWithPath:path];
            CFErrorRef error;
            CTFontManagerRegisterFontsForURL((__bridge CFURLRef)url, kCTFontManagerScopeNone, &error);
            error = nil;
        }
    });
}