问将嵌套类写入plist

EN

class Scale {
    var name: String
    var factor: Double
    var weights: [WeightSet] = []

    ...

 }

class WeightSet {
    var gauge: String
    var initial: Double
    var increment: Double
    var lengthUnit: String
    var weightUnit: String

   ...

}

var scales = [Scale]()

func readScales() {

    //read the plist file into input
    let input = NSArray(contentsOfFile: path)

    //loop through input
    for i in 0..<input!.count {

        //convert each element of input into a dictionary
        let scaleDict = input![i] as! NSDictionary

        //create a Scale object from the dictionary values
        let scale = Scale(name: scaleDict.valueForKey("name") as! String, factor: scaleDict.valueForKey("factor") as! Double)

        //convert the weights entry of the dictionary into an array of dictionaries
        let weights = scaleDict.valueForKey("weights") as! [NSDictionary]

        //loop through the array
        for weight in weights {

            //create a WeightSet object for each dictionary
            let weightSet = WeightSet(gauge: weight.valueForKey("gauge") as! String, initial:  weight.valueForKey("initial") as! Double, increment:  weight.valueForKey("increment") as! Double, lengthUnit:  weight.valueForKey("lengthUnit") as! String, weightUnit:  weight.valueForKey("weightUnit") as! String)

            //append the WeightSet object to the Scale Object
            scale.weights.append(weightSet)
        }

        //append the Scale object to the scales array
        scales.append(scale)
    }

    //print it to prove this worked!
    printScales()
}