There are two systems you can use on typing Mandarin Chinese on your phone or computer.
First it’s Pinyin, where you type in the Pinyin spelling into your device, and you get a list of characters to choose from.
Second it’s Handwriting, where you write the strokes of the characters on your device, and choose the right one from the options shown up.
On your phone (iPhone), simply go to Settings – General – Keyboard – Keyboards – Add new keyboard – choose Chinese (Simplified) Pinyin or Chinese (Simplified) Handwriting.
On your phone (Adroid), simply go to Settings – Language and Input – Choose Chinese Pinyin or Handwriting as you wish
On your computer (PC), simply download Google Pinyin, then use Ctrl + Shift to switch between English or Chinese typing into your computer.
We found a great post about how to install this settings on your phone from Written Chinese.com here with pictures step by step, it’s certainly useful.