void LoadImages()
{
// If we're already loading a set of images or there are no images left to load, just return
lock (locker) {
if (isLoadingBatch || firstThumbnailLoaded)
{
return;
}
else
{
isLoadingBatch = true;
}
}
// If we have a cursor, continue where we left off, otherwise set up new query
CKQueryOperation queryOp = null;
if (imageCursor != null)
{
queryOp = new CKQueryOperation(imageCursor);
}
else
{
CKQuery thumbnailQuery = new CKQuery(Image.RecordType, NSPredicate.FromValue(true));
thumbnailQuery.SortDescriptors = Utils.CreateCreationDateDescriptor(ascending: false);
queryOp = new CKQueryOperation(thumbnailQuery);
}
// We only want to download the thumbnails, not the full image
queryOp.DesiredKeys = new string[] {
Image.ThumbnailKey
};
queryOp.ResultsLimit = UpdateBy;
queryOp.RecordFetched = (CKRecord record) => {
ImageCollection.AddImageFromRecord(record);
InvokeOnMainThread(() => {
loadingImages.StopAnimating();
ImageCollection.ReloadData();
});
};
queryOp.Completed = (CKQueryCursor cursor, NSError error) => {
Error errorResponse = HandleError(error);
if (errorResponse == Error.Success)
{
imageCursor = cursor;
isLoadingBatch = false;
if (cursor == null)
{
firstThumbnailLoaded = true; // If cursor is nil, lock this method indefinitely (all images have been loaded)
}
}
else if (errorResponse == Error.Retry)
{
// If there's no specific number of seconds we're told to wait, default to 3
Utils.Retry(() => {
// Resets so we can load images again and then goes to load
isLoadingBatch = false;
LoadImages();
}, error);
}
else if (errorResponse == Error.Ignore)
{
// If we get an ignore error they're not often recoverable. I'll leave loadImages locked indefinitely (this is up to the developer)
Console.WriteLine("Error: {0}", error.Description);
string errorTitle = "Error";
string dismissButton = "Okay";
string errorMessage = "We couldn't fetch one or more of the thumbnails";
UIAlertController alert = UIAlertController.Create(errorTitle, errorMessage, UIAlertControllerStyle.Alert);
alert.AddAction(UIAlertAction.Create(dismissButton, UIAlertActionStyle.Cancel, null));
InvokeOnMainThread(() => PresentViewController(alert, true, null));
}
};
PublicCloudDatabase.AddOperation(queryOp);
}
