A citizen of a country outside of the EU who wants to move to Sweden to live with a family member must have a residence permit. In this context, husbands, wives, registered partners and co-habiting partners all count as family members, and so are children under the age of 18. Adult siblings or the parents of adult children are normally not able to obtain a residence permit as a family member.
The person in Sweden must be a Swedish citizen or somebody who holds either a permanent residence permit or a temporary residence permit with refugee status. There is also a so-called maintenance requirement, which means that the person who resides in Sweden must be able to support both him/herself and the family members applying for residence permits.
Please visit the Swedish Migration Agency's website for more information: Apply for a residence permit to live with someone in Sweden – Swedish Migration Agency