title: PHImageManager.requestImageForAsset returns low-res image in iOS swift
body: <p>I'm using Photos framework to handle images in iOS swift.
  When I try to get the image by using PHImageManager.defaultImanager().requestImageForAsset(), it works fine for most of images. That function returns two values: one is of scale 1, another is of scale 2. The image of scale 1 is high-res image, and the image of scale 2 is low-res image.
  But regarding some of images, it returns only low-res one.</p>
  
  <p>Does anyone know how to get high-res image for every PHAsset ?</p>
  
  <p>Here are my codes:</p>
  
  <p>Regarding some of images, it doesn't return the image of scale 1 (high-res), so it doesn't go through subFuncForDisplayCurrentImage()</p>
  
  <pre><code>    var targetSize:CGSize = CGSizeMake(UIScreen.mainScreen().bounds.size.width, UIScreen.mainScreen().bounds.size.height)
      var itemOptions = PHImageRequestOptions()
      itemOptions.networkAccessAllowed = true
  
      PHImageManager.defaultManager().requestImageForAsset(asset, targetSize: targetSize, contentMode: PHImageContentMode.AspectFit, options: itemOptions) { (result:UIImage!, info:[NSObject : AnyObject]!) -&gt; Void in
          if result != nil &amp;&amp; result.scale == 1 {
              self.subFuncForDisplayCurrentImage(result, ID: (asset?.localIdentifier)!)
          }
      }
  </code></pre>