private PHFetchResult AdjustAssets(PHFetchResult assets, PHFetchResultChangeDetails changes)
{
if (assets == null)
{
return(null);
}
var before = assets;
assets = changes.FetchResultAfterChanges;
foreach (var asset in before.OfType <PHAsset>())
{
if (!assets.Contains(asset))
{
AllAssets.Remove(asset);
}
}
foreach (var asset in assets.OfType <PHAsset>().OrderBy(a => a.CreationDate.SecondsSinceReferenceDate))
{
if (!AllAssets.Contains(asset))
{
AllAssets.Insert(0, asset);
}
}
return(assets);
}
private void OnAuthorized()
{
DispatchQueue.MainQueue.DispatchAsync(() =>
{
_imageManager = new PHCachingImageManager();
var options = new PHFetchOptions
{
SortDescriptors = new[] { new NSSortDescriptor("creationDate", false) }
};
var assets = new List <PHAsset>();
if (_mediaTypes.HasFlag(MediaType.Image))
{
_images = PHAsset.FetchAssets(PHAssetMediaType.Image, options);
assets.AddRange(_images.OfType <PHAsset>());
}
if (_mediaTypes.HasFlag(MediaType.Video))
{
_videos = PHAsset.FetchAssets(PHAssetMediaType.Video, options);
assets.AddRange(_videos.OfType <PHAsset>());
}
foreach (var asset in assets.OrderByDescending(a => a.CreationDate.SecondsSinceReferenceDate))
{
AllAssets.Add(asset);
}
ShowFirstImage();
AllAssets.CollectionChanged += AssetsCollectionChanged;
PHPhotoLibrary.SharedPhotoLibrary.RegisterChangeObserver(this);
});
}