connection(_:didWriteData:totalBytesWritten:expectedTotalBytes:)
Sent to the delegate to deliver progress information for a download of a URL asset to a destination file.
Declaration
optional func connection(_ connection: NSURLConnection, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, expectedTotalBytes: Int64)Parameters
- connection:
The URL connection object downloading the asset.
- bytesWritten:
The number of bytes written since the last call of this method.
- totalBytesWritten:
The total number of bytes of the downloading asset that have been written to the file.
- expectedTotalBytes:
The total number of bytes of the URL asset once it is completely downloaded and written to a file. This parameter can be zero if the total number of bytes is not known.
Discussion
This method is invoked repeatedly during the download of a URL asset to the destination file. The delegate typically uses the values of the three “bytes” parameters to update a progress indicator in the application’s user interface.