Hěn ɡāoxìnɡ hé nǐ liáotiān.

很高兴和你聊天。

It's been nice talking with you.

Notes:

很(hěn): very

高兴(ɡāoxìnɡ): happy, glad

和(hé): and, with

你(nǐ): you

聊天(liáotiān): to chat, to talk

Example:

A: 很高兴和你聊天。

    Hěn ɡāoxìnɡ hé nǐ liáotiān. 

    It's been nice talking with you.

B: 我也是。

    Wǒ yě shì.

    Me too.

Level:　★★★☆☆