类型'[String：Any]'在Swift中没有下标成员

Question

I am trying to get information from a json result and append and access certain key values. However, I am getting the error "Type '[String:Any]' has no subscript members.

        let json = try? JSONSerialization.jsonObject(with: data!, options: []) as! [String: Any]
        for case let studentsInfo in json["results"] {
            if let studentInfo = StudentResults(json: result) {
                let name = firstName + " " + lastName
                StudentsResults.append(name)
            }

This is also the struct that I have placed in an extension.

struct StudentResults{
    let firstName: String
    let lastName: String
    let latitude: Double
    let longitude: Double
    let mapString:String
    let mediaURL: String
    let objectID:String
    let uniqueKey: String
    let updatedAt: String
}

convenience init?(json: [String: Any]) {
    guard let firstName = json["firstName"] as? String,
          let lastName = json["lastName"] as? String
        else {
            return nil
    }
    return nil

This is also my GitHub page for this project if you would like to take a look at it

https://github.com/SteveBurgos95/UdacityMapProject

Answer 1

It appears to me that the problem is with this line of code:

let json = try? JSONSerialization.jsonObject(with: data!, options: []) as! [String: Any]

Whilst you are force casting it here as! [String: Any] as! [String: Any] , the try? is giving you an optional value.

You have two options. You can be a crazy person and change try? to try! , or you can take the safer approach and wrap the code like so:

do {
    guard let json = try JSONSerialization.jsonObject(with: data!, options: []) as [String: Any] else { return }
    …
} catch {
    // HANDLE ERROR
}