One of the blues (Lycaenidae family), possibly a Common blue (Polyommatus icarus), but one would have to see the top side of the butterfly and know in what type of habitat it was seen to make a more confident ID.
As @KevinB has said knowing the habitat might help narrow this down to species. I would make a guess at Common blue due to your photo being taken back in June and Holly blue are only on the wing in early spring and from July onwards. It could of course be another blue as I'm not well read on what species occur in Sweden.
