float dist = sqrt(pow(self.pos.x - ball.pos.x, 2) + pow(self.pos.y - ball.pos.y, 2));

float minLength = (self.sprite.contentSize.height/2 + ball.sprite.contentSize.height/2);
float width = self.pos.x - ball.pos.x;
float height = self.pos.y - ball.pos.y;
float delta = minLength/dist;
float x, y = 0.0;

x = width * delta;
y = height * delta;

x -= width;
y -= height;

x *= -1;
y *= -1;

ball.pos = CGPointMake(ball.pos.x + x, ball.pos.y + y);