SAN FRANCISCO — The developer of Pikinis, an app that combs Facebook for pictures of women in bikinis, is suing the social-networking company for blocking its access to user photos.

In 2010 Facebook Inc. announced it would allow third-party apps to access users’ photos and other personal information, according to the complaint filed Friday in San Mateo County Superior Court. The idea was to encourage developers to create apps that could work with Facebook and enhance the user experience. New York developer Six4Three LLC’s contribution was Pikinis, an app that uses pattern-recognition technology to find swimsuit photos of users’ Facebook friends.