You can change your keyboard settings and add a Chinese (pinyin) keyboard. You shouldn't need to download any third party programs.
When you've changed your keyboard, you can press the keyboard icon to change the current language settings. This will allow you to type in pinyin.
How it works is you type pinyin, e.g. nihao 你好, it will be automatically translated to the chinese characters corresponding to the pinyin you just type.
This works both on IOS or Windows.
