title: How to know image present at the url
body: <p>I have url for image picked using <code>ELCImagePickerController</code>. I stored the url for future reference.</p>
  
  <p>I get that URL using:</p>
  
  <pre><code>[dict valueForKey:UIImagePickerControllerReferenceURL];
  </code></pre>
  
  <p>Now the problem arises when after some time user deleted that particular image from photo library
  and I am going to access that image using URL.
  My app does not get crashed.</p>
  
  <p>I have tried using NSUrl method</p>
  
  <pre><code>[imagePath checkResourceIsReachableAndReturnError:&amp;err]
  </code></pre>
  
  <p>as well i tried something like:</p>
  
  <pre><code>-(BOOL)findImage:(NSURL*)path
  {
      dispatch_group_t group = dispatch_group_create();
      dispatch_group_enter(group);
      __block BOOL flag=YES;
      ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
      {
          ALAssetRepresentation *rep = [myasset defaultRepresentation];
          CGImageRef iref = [rep fullScreenImage];
          if (iref) {
              flag=YES;
              dispatch_group_leave(group);
          }
      };
      ALAssetsLibraryAccessFailureBlock failureblock  = ^(NSError *myerror)
      {
          NSLog(@"cant get image - %@",[myerror localizedDescription]);
          flag=NO;
      };
      ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
      [assetslibrary assetForURL:path resultBlock:resultblock failureBlock:failureblock];
  
      dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
      dispatch_release(group);
      [assetslibrary release];
  
      return flag;
  }
  </code></pre>
  
  <p>Sample url : </p>
  
  <pre><code>assets-library://asset/asset.JPG?id=E862927E-E646-448A-9EB6-A7D48668B3DC&amp;ext=JPG
  </code></pre>
  
  <p>But no success.</p>
  
  <p>How to know that image present at particular URL.</p>
  
  <p>If any one can help me out on this will be appreciable.</p>
  
  <p>Thanks in advance.</p>