NKAssetDownload Class Reference

Overview

An instance of the NKAssetDownload class represents an asset that is being downloaded (or has downloaded) for an issue of a Newsstand application.

An asset can be either a component of an issue—for example, an HTML file, a plain-text file, an image, or a video—or the entire issue compressed in a ZIP or other archive. The latter approach is recommended.

You create an NKAssetDownload instance using the NKIssue method addAssetWithRequest:; you pass into this method an NSURLRequest object that contains the URL locating the asset on the application’s server. To begin downloading the asset, call downloadWithDelegate: on the NKAssetDownload object. The delegate specified as the parameter of this message must adopt the NSURLConnectionDownloadDelegate protocol. It should implement the three methods specific to handling downloads of issue assets:

• connection:didWriteData:totalBytesWritten:expectedTotalBytes: — The delegate updates a progress indicator as the download proceeds.

• connectionDidResumeDownloading:totalBytesWritten:expectedTotalBytes: — The delegate updates a progress indicator as a stopped download resumes.

• connectionDidFinishDownloading:destinationURL: — The delegate moves or otherwise processes the downloaded asset.

If a Newsstand application terminates while asset downloading is underway, the downloading continues in the background. When the asset is downloaded, the application is brought to the foreground if it has a newsstand-content value for the “UIBackgroundModes” in Information Property List Key Reference array in the information property list. It should obtain an instance of NKIssue and iterate through the NKAssetDownload objects in the downloadingAssets array; for each object, call downloadWithDelegate: on it and have the delegate process the remaining downloads.