Don't write loops if there are STL algorithms for this task:
std::fill(kolizia, kolizia+9, false);
Or use
std::array, which is a good idea anyway:
std::array<bool, 9> kolizja;
...
kolizja.fill(false);
Or initialize the array directly:
mysz::mysz(void)
: kolizja() // sets all elements to false
{
}
By the way, you should avoid
using in header files. Why don't you explicitly write
sf::Vector2i? That's the purpose of namespaces