CODEWITHSUNDEEP
swiftstructsavenscoding
Peter Silie
Peter Silie

Reputation: 875

Helperclass for saving structs with NSCoding

I want to write a function for saving my struct Array. I know, that using NSCoding is the right way, but only available to classes. But I found a workaround using a class including the struct itself: 

extension EXIFData {
    class EXIFDataClass: NSObject, NSCoding {

        var exifData: EXIFData?
...
}

But how do I use it (call it)? E.g. defined as

var exif : EXIFData

or (next step)

var exifs : [EXIFData]

I like to use as much as possible of the actual features of Swift 3.0, because I'm just starting. I found some different solutions for older styles and versions of Swift.

Upvotes: 0

Views: 283

Answers (1)

Benjamin Lowry
Benjamin Lowry

Reputation: 3789

I am not sure what your class EXIFData is, but I think that you are better off saving a class that contains a EXIFData object.

Say for example you need to save a bunch of different types of data including EXIFData, then you could create a class like the following which decodes, encodes, and initializes a class with an EXIFData type:

class UserData: NSObject, NSCoding {

    var exifData: EXIFData
    //other variables of data....

    required init?(coder aDecoder: NSCoder) {
        exifData = aDecoder.decodeObject(forKey: "EXIFData") as! EXIFData
        //decode other values
    }

    init(exifData: EXIFData) {
        self.exifData = exifData
        //intialize other values
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(exifData, forKey: "EXIFData")
        //encode other values
    }

}

Then you could initialize your class like so:

var myUserData = UserData(...) //initialize with EXIFData

And then call your user "EXIFData" like so:

myUserData.exifData

Upvotes: 1

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