Is it okay to use ain't in formal conversation? I know ain't can be used for am not, is not, are not, have not, has not. So if I can use it in day-to-day life, it will be easier for me I guess.
In regular usage, nowadays we use short spellings of words in speaking or writing. For example: They are in the cinema. => They're in the cinema. We have been waiting for me. => We've been waiting ...