We construct a sequence of finite sets which approximates, with arbitrarily small and controlled error, the attractor set of a (finite or countable) given iterated function system of order m. Our main tool are the so-called α-dense curves which are from the Hausdorff-Pompeiu distance point of view, a generalization of the space-filling curves. Also we prove that, under suitable conditions, our result can be used to approximate infinite-dimensional fractals generated by integral equations of Volterra type.