title: Image asset size in Xcode interface builder
body: <p>If I add an image view onto interface builder in Xcode and it has a size of 200 x 100 (size in Xcode), how do I know what size to make the image asset for 1x 2x and 3x. </p>
  
  <p>If I make it 600x300 pixels in photoshop for the 3x and then try to use this image it doesn't look very clear on an iPhone 7 plus so how do I know what resolution the image assets should be for a given image view size</p>