The data source for the photo scrubber.
A scrubber view's purpose is for instantly flipping through an album of photos. As such, it's crucial that your implementation of the data source performs blazingly fast. When the scrubber requests a thumbnail from you you should not be hitting the disk or blocking on a network call. If you don't have the thumbnail available at that exact moment, fire off an asynchronous load request (using NIReadFileFromDiskOperation or NIHTTPRequest) and return nil. Once the thumbnail is loaded, call didLoadThumbnail:atIndex: to notify the scrubber that it can display the thumbnail now.
It is not recommended to use high-res images for your scrubber thumbnails. This is because the scrubber will keep a large set of images in memory and if you're giving it high-resolution images then you'll find that your app quickly burns through memory. If you don't have access to thumbnails from whatever API you're using then you should consider not using a scrubber.
Fetching Required Information
|(UIImage *)||- photoScrubberView:thumbnailAtIndex:|
Fetches the total number of photos in the scroll view.
The value returned in this method will be cached by the scroll view until reloadData is called again.
Fetch the thumbnail image for the given photo index.
Please read and understand the performance considerations for this data source.