How to use a class category Objective C in Swift?

Question

I have a class category wrote in Objective C. I need use this in Swift. But I don't know how to declare this to call.

      var vcfPart: NSDictionary = [kSKPSMTPPartContentTypeKey:"video/quicktime;\r\n\tx-unix-mode=0644;\r\n\tname=\"video.mp4\"", kSKPSMTPPartContentTypeKey:"attachment;\r\n\tfilename=\"video.mp4\"", kSKPSMTPPartContentDispositionKey: self.rep ,kSKPSMTPPartMessageKey:"base64", kSKPSMTPPartContentTransferEncodingKey: "8bit"]

data is of type NSData. I need encode this with NSData+Base64Additions https://github.com/kailoa/iphone-smtp/blob/master/Classes/NSData%2BBase64Additions.m

in objective c call:

 NSDictionary * vcfPart3 = [NSDictionary dictionaryWithObjectsAndKeys:@"video/quicktime;\r\n\tx-unix-mode=0644;\r\n\tname=\"video.mp4\"",kSKPSMTPPartContentTypeKey,
                           @"attachment;\r\n\tfilename=\"video.mp4\"",kSKPSMTPPartContentDispositionKey, [data encodeWrappedBase64ForData], kSKPSMTPPartMessageKey, @"base64", kSKPSMTPPartContentTransferEncodingKey, nil];

I don't know how to declare this in Swift with an extension..

How can use this in Swift?

Thanks!

Answer 1

Extensions can't contain stored properties, as I'm sure the compiler has already informed you. If this is actually a constant, express it as a computed property and you'll be fine.

In other words, this is illegal in an extension:

let i = 4

But this is legal:

var i : Int {
    return 4
}