Xtykutl

In Java we can use constructors in order to pass initial values into a class. Is this possible in swift?

For example, in the line below I am trying to add an object, which should include all the values you can see in the function that is within it, into an array called arrayOfMedia.

self.arrayOfMedia.append(Media().getUsersMedia(image: image!, postNum: anyPosts.key, userID: user))

I cannot do this however and get the error below.

Cannot convert value of type '()' to expected argument type 'Media'

I do not want to have to initialize the class as the values going into it vary (sometimes a video and sometimes a image)

Okay, so that makes no sense, you have a class which is a container for some data, some of which is optional (either you have an image or a video), why not supply two different initialisers for the two different use cases ... just like you would in Java?

There's a few ways you "might" achieve this, this is just one...

class Media {

    var image: UIImage?

    var video: Data?

    let postKey: Int

    let userId: Int



    internal required init(postKey: Int, userId: Int) {

        self.postKey = postKey

        self.userId = userId

    }



    convenience init(image: UIImage, postKey: Int, userId: Int) {

        self.init(postKey: postKey, userId: userId)

        self.image = image

    }



    convenience init(video: Data, postKey: Int, userId: Int) {

        self.init(postKey: postKey, userId: userId)

        self.video = video

    }

}

Also, note, you could have simply provided a single initialiser, something like...

init(image: UIImage? = nil, video: Data? = nil, postKey: Int, userId: Int) {...}

but this doesn't constraint the user to one or the other type (they can still pass nil for both values)

Another approach might be to make use of a protocol to describe the basic/common properties of Media and then implement the different requirements (directly as structs or classs or indirectly as additional protocols)

For example...

protocol Media  {

    var postKey: Int { get }

    var userId: Int { get }

}



struct VideoMedia: Media {

    let postKey: Int

    let userId: Int

    let video: Data

}



struct ImageMedia: Media {

    let postKey: Int

    let userId: Int

    let image: UIImage

}

For what it's worth, in this case I would use enums to wrap your media types.

enum MediaType {

    case image(UIImage)

    case video(Data) 

}

Then you have Type safe access without requiring optionals:

struct Media {

    let postKey: Int

    let userId: Int

    let mediaType: MediaType

}



let video = Media(postKey: 1, userId: 2, mediaType: .video(dataVariable))

let image = Media(postKey: 2, userId: 3, mediaType: .image(imageVariable))