修改self.title标题颜色字号等

self.title = @"改变标题字体颜色";

       NSDictionary *dic = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:[UIColor blueColor], [UIFont systemFontOfSize:20 weight:20], nil] forKeys:[NSArray arrayWithObjects:NSForegroundColorAttributeName, NSFontAttributeName, nil]];

    self.navigationController.navigationBar.titleTextAttributes = dic;