title: Why Rectangle drew on UIView is blurry but adding layers to UIView is not when zoom up the UIView?
body: <p>I am always thinking of this question.</p>
  
  <p>My case is that I need to show many grids on view, I have two plans.</p>
  
  <p>1, draw a lot of rectangles on UIView. I tried it, but when I zoomed up the view, the line is blurry.</p>
  
  <p>2, add a lot of CALayer to UIView. I tried this too, it makes sense, but I don't know if this way will need more memory than way #1.</p>
  
  <p>Please answer me if I can make it not blurry if I use the way #1, thanks.</p>