An instance of the
NKAsset class represents an asset that is being downloaded (or has downloaded) for an issue of a Newsstand application.
- iOS 5.0+
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
NKAsset instance using the
add; 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
download(with:) on the
NKAsset object. The delegate specified as the parameter of this message must adopt the
NSURLConnection protocol. It should implement the three methods specific to handling downloads of issue assets:
connection(_:— The delegate updates a progress indicator as the download proceeds.
did Write Data: total Bytes Written: expected Total Bytes:)
connection— The delegate updates a progress indicator as a stopped download resumes.
Did Resume Downloading(_: total Bytes Written: expected Total Bytes:)
connection— The delegate moves or otherwise processes the downloaded asset.
Did Finish Downloading(_: destination URL:)
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 array in the information property list. It should obtain an instance of
NKIssue and iterate through the
NKAsset objects in the
downloading array; for each object, call
download(with:) on it and have the delegate process the remaining downloads.