parameterized enums in swift that don't crash xcode

parameterized_enum.swift

// Playground - noun: a place where people can play

import Foundation

struct ResultType<T: NSObject> {
    var _value: [T]

    var value: T {
    get {
        return _value[0]
    }
    set {
        _value = [newValue]
    }
    }

    init(value: T) {
        _value = [value]
    }
}

enum ApiResult<T: NSObject> {
    case Success(ResultType<T>)
    case Error(String, NSError)
}

func something(val: ApiResult<NSString>) {
    switch val {
    case .Success(let val2):
        println(val2.value)
    default:
        println("wah wah")
    }
}

let res2 = ApiResult<NSString>.Success(ResultType(value: NSString(string: "lololol")))

something(res2)