无法下标[AnyObject]的值？ 索引类型为String

Question

In the function below, I am trying to find the current user in the Users table on Parse.com by the username and add/update a field value called salaryMode .

Below is my function and the error I am getting:

Error I see :

Cannot subscript a value of [AnyObject]? with an index of type String

func saveUserSalaryInfo() {

    var query = PFQuery(className:"User")
    query.whereKey("username", equalTo: PFUser.currentUser()!.username!)
    query.findObjectsInBackgroundWithBlock {
        (users: [AnyObject]?, error: NSError?) -> Void in
        if error != nil {

            users["salaryMode"] = self.salaryMode

        } else {
            // Log details of the failure
            //NSLog("Error: %@ %@", error, error.userInfo)
        }
    }

}

Answer 1

Short answer: no, you cannot access an array using a subscript of type String

Long answer:

users: [AnyObject]? This means that the user variable holds an optional type. So it can be nil, or if anything, an Array of AnyObject (which allows for anything really). But this is an array: so index-based access needs numbers.

You're confusing this for a Dictionary, which has a similar syntax to access elements using a key

// Array

let array: [String] = ["one", "two", "three"]

array[0] // "one"

array["one"]   // error

// Dictionary

let brothers = ["one": "Groucho", "two": "Chico", "three": "Harpo"]

brothers["one"] // Groucho