Hello, I am a Cantonese. Actually, Cantonese do not have its own letter or character, when we use cantonese to chat on WeChat, we just borrow the characters from Mandrain. So, if you want to learn Cantonese, you can just listen and watch Cantonese movie, TV drama, etc,, the so-called textbook doesn't help at all, It is nonsense for us. if you know some Mandrain that will be very helpful. But, of cause, you don't need to learn Mandrain first before you learn Cantonese. Cantonese is just like a song, you need to learn its tone, pronunciation.