ios - SpriteKit SKSpriteNode filles entire scene -

i'm trying add skspritendoe scene reason image fills entire scene if image size 50x50 pixels.

here's code:

    let sprite = skspritenode(imagenamed:"my-sprite")     sprite.position = cgpoint(x: cgrectgetmidx(self.frame),                                 y: cgrectgetmidy(self.frame))     addchild(sprite) 

thanks