Swiftyjson: .doubleValue successfully converts string into Double while .double returns nil

[Causaelity]

What did you do?

Pulling JSON from: https://apiv2.bitcoinaverage.com/indices/global/ticker/BTCUSD which currently returns:

{
"ask": "6746.95",
"bid": "6738.92",
"last": "6745.46",
"high": "7331.56",
"low": "6722.81",
"open": {
"hour": "7158.04",
"day": "7158.04",
"week": "7024.12",
"month": "4822.05",
"month_3": "3405.78",
"month_6": "1744.77",
"year": "719.80"
},
"averages": {
"day": "7092.52",
"week": "7113.14",
"month": "6776.50"
},
"volume": "182053.35813936",
"changes": {
"price": {
"hour": "-412.58",
"day": "-412.58",
"week": "-278.66",
"month": "1923.41",
"month_3": "3339.68",
"month_6": "5000.69",
"year": "6025.66"
},
"percent": {
"hour": "-5.76",
"day": "-5.76",
"week": "-3.97",
"month": "39.89",
"month_3": "98.06",
"month_6": "286.61",
"year": "837.13"
}
},
"volume_percent": "79.66",
"timestamp": 1510336968,
"display_timestamp": "2017-11-10 18:02:48"
}

was attempting to extract the "last" value as a double by:

if let lastValue = json["last"].double { print(lastValue) }
// did other things with the lastValue than just print.

What did you expect to happen?

I expected the string would convert successfully as Double? or nil if the data was not available. Using json["last"].doubleValue works.

What actually happened instead?

The typecast failed and my "else" segment of code ran instead.

Environment

List the software versions you're using:

• SwiftyJSON: 4.0.0
• Xcode Version: 9.1 (9B55) (Open Xcode; In menubar: Xcode > About Xcode)
• Swift Version: Xcode.Default (Open Xcode Preferences; Components > Toolchains. If none, use Xcode Default.)

Please also mention which package manager you used and its version. Delete the
other package managers in this list:

• Cocoapods: 1.3.1 (Use pod --version in Terminal)

Project that demonstrates the issue

https://github.com/Causaelity/SwiftyJSONDoubleBug

[Causaelity]

Looking at your code I think this is because public var numberValue: NSNumber has a .string case where public var number: NSNumber? does not. Adding the following code fixed this problem:

   //Optional number
    public var number: NSNumber? {
        get {
            switch self.type {
            case .string:
                let decimal: NSDecimalNumber? = NSDecimalNumber(string: self.object as? String)
                if decimal == NSDecimalNumber.notANumber {  // indicates parse error
                    return nil
                }
                return decimal
            case .number:
                return self.rawNumber
            case .bool:
                return NSNumber(value: self.rawBool ? 1 : 0)
            default:
                return nil
            }
        }
        set {
            self.object = newValue ?? NSNull()
        }
    }

[Causaelity]

Forked the code, added the fix and provided some new unit tests, created pull request.

[ncltg]

Sounds like this issue is still not merged into v4.1.0 as i'm facing the exact same problem.

Any update on that ?

[Causaelity]

I'm not sure how they decide what to merge vs not.

[mortenholmgaard]

Same problem with .bool and .int