Type Method


Returns whether a URL download object can resume a download that was decoded with the specified MIME type.


class func canResumeDownloadDecoded(withEncodingMIMEType MIMEType: String) -> Bool



The MIME type the caller wants to know about.

Return Value

true if the URL download object can resume a download that was decoded with the specified MIME type, false otherwise.


The MIME type of a file, in conjunction with the value returned by the download(_:shouldDecodeSourceDataOfMIMEType:) delegate method, determines whether the NSURLDownload class should decode or decompress the incoming data as it is received.

Some compression techniques, such as the DEFLATE algorithm (gzip) use symbol dictionaries that vary during the compression process, making it impractical to decompress only a portion of the data starting in the middle. For this reason, this method returns false unless both of the following conditions are met:

  • The MIME type is of a type that the NSURLDownload class knows how to decompress or decode.

  • The decoding can be safely resumed.

In practice, this method returns true for MacBinary and BinHex, otherwise false.

If your app needs to be able to resume file downloads in gzip format, your download(_:shouldDecodeSourceDataOfMIMEType:) method must return false, and you must decode the resulting file yourself after you finish downloading it in its entirety.

See Also

Resuming partial downloads

init(resumeData: Data, delegate: NSURLDownloadDelegate?, path: String)

Returns an initialized NSURLDownload object that will resume downloading the specified data to the specified file and begins the download.

var resumeData: Data?

Returns the resume data for a download that is not yet complete.

var deletesFileUponFailure: Bool

Returns whether the receiver deletes partially downloaded files when a download stops prematurely.