通过下标的Swift字典访问值抛出错误

Question

Accessing a Swift Dictionary value through subscript syntax is gives error Ambiguous reference to member 'subscript'

Here is the code

class Model {

    struct Keys {
        static let type :String = "type" //RowType
        static let details :String = "details"
    }

    var type :RowType = .None
    var details :[Detail] = []

    init(with dictionary:Dictionary<String, Any>) {

        if let type = dictionary[Keys.type] as? String {
            self.type = self.rowTypeFromString(type: type)
        }

        if let detailsObj = dictionary[Keys.details] as? Array { //Error : Ambiguous reference to member 'subscript'


       }
    }

}

if i remove the type casting as? Array as? Array at the end of optional-binding it compiles fine

I am expecting the value of details key to be an Array , I know that i can use [String,Any] instead of Dictionary<Key, Value> , What is causing the issue ?

Answer 1

Array doesn't work like NSArray, you explicitly need to tell what type your array is storing.

If you want to store Detail objects in it, the proper syntax is Array<Detail> or simply [ Detail]

if let detailsObj = dictionary[Keys.details] as? Array<Detail> {

}

Answer 2

Issue is solved by explicitly specifying the Type of objects the array contains, In my case it was Array<[String:Any]>

if let detailsObj = dictionary[Keys.details] as? Array<[String:Any]> { //we should also specify what type is present inside Array


}

Credits: @Hamish, @Dávid Pásztor

Thanks!