How to write init method in Swift?

Question

I want to write an init method in Swift. Here I initialize an NSObject class in Objective-C:

-(id)initWithNewsDictionary:(NSDictionary *)dictionary
{
    self = [super init];
    if (self) {
        self.title           = dictionary[@"title"];
        self.shortDescription = dictionary[@"description"];
        self.newsDescription = dictionary[@"content:encoded"];
        self.link            = dictionary[@"link"];
        self.pubDate         = [self getDate:dictionary[@"pubDate"]];

    }
    return self;
}

How can I write this method in Swift ?

Download and read the Swift Language Guide ;-) https://itunes.apple.com/us/book/the-swift-programming-language/id881256329?mt=11 — Nick, Jun 19 '14 at 08:45
it may be helpful to understand the _init_ procedure as well from the book: https://developer.apple.com/library/prerelease/ios/documentation/swift/conceptual/swift_programming_language/Initialization.html, additionally the _deinit_ procedure is still recommended for reading. — holex, Jun 19 '14 at 08:47

holex · Accepted Answer · 2014-06-19T09:32:01.910

that could be good bases for your class, I guess:

class MyClass {

    // you may need to set the proper types in accordance with your dictionarty's content
    var title: String?
    var shortDescription: String?
    var newsDescription: String?
    var link: NSURL?
    var pubDate: NSDate?

    //

    init () {
        // uncomment this line if your class has been inherited from any other class
        //super.init()
    }

    //

    convenience init(_ dictionary: Dictionary<String, AnyObject>) {
        self.init()

        title = dictionary["title"] as? NSString
        shortDescription = dictionary["shortDescription"] as? NSString
        newsDescription = dictionary["newsDescription"] as? NSString
        link = dictionary["link"] as? NSURL
        pubDate = self.getDate(dictionary["pubDate"])

    }

    //

    func getDate(object: AnyObject?) -> NSDate? {
        // parse the object as a date here and replace the next line for your wish...
        return object as? NSDate
    }

}

advanced-mode

I would like to avoid to copy-pand-paste the keys in a project, so I'd put the possible keys into e.g. an enum like this:

enum MyKeys : Int {
    case KeyTitle, KeyShortDescription, KeyNewsDescription, KeyLink, KeyPubDate
    func toKey() -> String! {
        switch self {
        case .KeyLink:
            return "title"
        case .KeyNewsDescription:
            return "newsDescription"
        case .KeyPubDate:
            return "pubDate"
        case .KeyShortDescription:
            return "shortDescription"
        case .KeyTitle:
            return "title"
        default:
            return ""
        }
    }
}

and you can improve your convenience init(...) method like e.g. this, and in the future you can avoid any possible mistyping of the keys in your code:

convenience init(_ dictionary: Dictionary<String, AnyObject>) {
    self.init()

    title = dictionary[MyKeys.KeyTitle.toKey()] as? NSString
    shortDescription = dictionary[MyKeys.KeyShortDescription.toKey()] as? NSString
    newsDescription = dictionary[MyKeys.KeyNewsDescription.toKey()] as? NSString
    link = dictionary[MyKeys.KeyLink.toKey()] as? NSURL
    pubDate = self.getDate(dictionary[MyKeys.KeyPubDate.toKey()])

}

NOTE: that is just a raw idea of how you could do it, it is not necessary to use conveniece initializer at all, but it looked obvious choice regarding I don't know anything about your final class – you have shared one method only.

score 12 · Answer 2 · edited Mar 19 '20 at 05:55

12

class myClass {
    var text: String
    var response: String?

    init(text: String) {
        self.text = text
    }
}

See Swift: Initialization

edited Mar 19 '20 at 05:55

pkamb

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answered Jun 19 '14 at 08:44

Shai

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score 5 · Answer 3 · edited Mar 18 '20 at 21:23

5

Do not need for call this method from other class it will get called automatically

override init()
{
    super.init()
    // synthesize.delegate = self
    // println("my array elements are \(readingData)")
}

edited Mar 18 '20 at 21:23

pkamb

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answered Dec 11 '14 at 09:47

abdul sathar

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score 0 · Answer 4 · edited Mar 19 '20 at 05:54

0

try:

initWithDictionary(dictionary : NSDictionary) {
   init()
   self.title = "... etc"
}

Source:

https://docs.swift.org/swift-book/LanguageGuide/Initialization.html

edited Mar 19 '20 at 05:54

pkamb

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answered Jun 19 '14 at 08:47

CW0007007

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How to write init method in Swift?

4 Answers4

advanced-mode

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