I'm making an app where I'm using sketch 3 to create image assets. First, I design something, click "make exportable" in the lower-right, chooses 0.5x and export it to somewhere on my Mac. Then, I drag the asset (*.png file) into Xcode 6 and for instance created an imageview with that asset as image - but if I look closely when running the app on my phone, the asset looks slightly blurred or not 100% focused, as if some of the color made it onto another pixel.. Does anyone have a clue on this? How can I make it sharper?