Is encoding swift array of optionals possible?

Question

I'd like to be able to encode a class with an array of optional values. Xcode errors with "Cannot invoke 'encode object' with an argument list of type '([SKSpriteNode?], for key: String').

 class MyCustomNode: SKNode {

     var possibleSprites:[SKSpriteNode?] = [nil, nil, nil, nil, nil, nil, nil]

 ...

 }

override func encodeWithCoder(aCoder: NSCoder) {

    aCoder.encodeObject(self.possibleSprites, forKey: "POSSIBLESPRITES")
    super.encodeWithCoder(aCoder)

}

Is this possible to achieve? If not, what are other options?

Question on proper decoding...

With the following,

 let x:[AnyObject!] = aDecoder.decodeObjectForKey("POSSIBLESPRITES") as! [AnyObject]
 self.possibleSprites = x.map { $0 == NSNull() ? nil : $0 }

I get Xcode error: “Cannot invoke 'map' with an argument list of type '((_) -> _)'”

I believe it has to do with the return type, but not sure how to solve...

How about var a:[AnyObject] = [NSNull(),NSNull()]

Tien Dinh
– Tien Dinh

2015-07-05 01:57:33 +00:00
Commented Jul 5, 2015 at 1:57 — Tien Dinh
– Tien Dinh, Commented Jul 5, 2015 at 1:57

Code Different · Accepted Answer · 2015-07-05 23:59:09Z

1

With Objective-C you can't encoding a nil pointer either. You need to map self.possibleSprites to an array of AnyObject? and use NSNull in place of nil.

let x : [AnyObject!] = self.possibleSprites.map { $0 == nil ? NSNull() : $0 }
aCoder.encodeObject(x, forKey: "POSSIBLESPRITES")

Just remember to decode it properly on the way back.

answered Jul 5, 2015 at 23:59

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