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;