Cannot use mutating member on immutable value array is a get-only property swift 3

Question

I understand the problem, but I don't know how to solve it, I found other thread, but they are very specific problem. I have my for var:

    static var DeliveryStatusArray =
    [
        "claimable": [],
        "onTime": [],
        "future": [],
        "claimDone": [],
        "tooOld": [],
    ]

My function is :

    static func moreCard(status:String, newJson: JSON)
{
    var json = JSON(DeliveryStatusArray[status] as Any)
    var tmpArray = json[0]["cards"].arrayValue

    newJson["cards"].array?.insert(tmpArray, at: 0)
    DashboardManager.DeliveryStatusArray[status]?.removeAll()
    DashboardManager.DeliveryStatusArray[status] = tmpArray
}

In this function I want to insert at the begining of newJson["cards"] tmpArray. In second time I need to pass newJson at DeliveryStatusArray["status"]. I got my error on the line

newJson["cards"].array?.insert(tmpArray, at: 0)

In my view, the prototype of my function is:DashboardManager.moreCard(status: section, newJson: json["data"])

Nishant Bhindi · Accepted Answer · 2017-03-22 11:34:04Z

1

Swift only allows constants as the method parameter. In your case to fix the problem, you can use the inout parameter in the method as below.

  static func moreCard(status:String, newJson: inout JSON)
  {
     var json = JSON(DeliveryStatusArray[status] as Any)
     var tmpArray = json[0]["cards"].arrayValue

     newJson["cards"].array?.insert(tmpArray, at: 0)
     DashboardManager.DeliveryStatusArray[status]?.removeAll()
     DashboardManager.DeliveryStatusArray[status] = tmpArray
  }

answered Mar 22, 2017 at 11:34

Nishant Bhindi

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2 Comments

Badr Filali Over a year ago

Do I need to change my prototype ? When I change it to DashboardManager.moreCard(status: section, newJson: json["data"]) I still have the same error, and if I don't change the prototype, I have the error Passing value of type 'Json' to an inout parameter requires explicit &

Nishant Bhindi Over a year ago

No just pass pre-created prototype object in the inout parameter and you will be able to mutate that object in your method. Parameter to be passed in the method will be DashboardManager.moreCard(status: section, newJson: &json["data"]) or var jsondata = json["data"] then DashboardManager.moreCard(status: section, newJson: &jsondata)

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