You can apply for tourist visa for visiting friends at Chinese Embassy in Sweden, your friend should send you an invitation letter, the copy of his China visa or residence permit or work permit and copy of his passport, if your friend is chinese, he just need to send an invitation letter and the copy of his ID card. you also need to prepare the below documents:
(I) Original passport with validity more than six months and minimum 2 blank visa pages;

(II) Photocopy of the first 2 pages (personal information) of the passport and the recent Chinese visa page if there is any;

(II) One fully completed visa application form in Chinese or English, attached with one of the applicant's recent color photograph (30mm X 40mm)