What is the recommended way to assign an optional Swift property a decoded primitive with `NSCoder`?

Question

Curiosity OP

Created Apr ’23

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For an example like:

someOptionalDouble = aDecoder.decodeDouble(forKey: "SomeKey")

I'm not sure how to avoid a crash if the double was encoded as nil, while also avoiding Apple's console warning that decoding primitives as an object will become an error in the future.

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Answer 1

DTS Engineer OP

Apple

Apr ’23

I’m not sure if this is the best way to do this, but one option is to preflight the decode with containsValue(forKey:).

extension NSCoder {
    
    func decodeOptionalDouble(forKey key: String) -> Double? {
        guard self.containsValue(forKey: key) else { return nil }
        return self.decodeDouble(forKey: key)
    }
}

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