Could not cast value of type '_SwiftValue' error

Question

I'm trying to fill my arrays with datas in JSONArray that i get from server and I'm doing that with this code(swift 3 Xcode 8):

 func parseReservationJson(_ anyObject:Array<AnyObject>){
            nodes.removeAll()
            reservations.removeAll()
            for anyObj in anyObject{
                let client_name = (anyObj["client_name"] as? String) ?? ""
                let client_family  =  (anyObj["client_family"] as? String) ?? ""
                let ft_of_time = ((anyObj["ft_of_time"] as AnyObject as! NSString).substring(to: 5) as NSString)
            }
    }

But I'm getting this error for the last line of for statement :

Could not cast value of type '_SwiftValue' (0x112d8a898) to 'NSString' (0x11003eab8).

what is wrong?

What is `_SwiftValue`? You are going to cast the result of `anyObj["ft_of_time"]` to `NSString` and the compiler says you can't. And use the native Swift `substringTo`. I know it's more difficult to get the appropriate index but it's more reliable. — vadian, Sep 17 '16 at 08:31
I wouldn't ask if i knew the answer! i don't have any idea why I'm getting that error for converting `AnyObject` to `NSString` @vadian — Amir_P, Sep 17 '16 at 08:33
OK, next question: What is the actual type of the result of `anyObj["ft_of_time"]`? — vadian, Sep 17 '16 at 08:35
@Amir_P Yes, I realised after posting my comment that it'd be an optional. The problem is that Swift has no idea how to bridge optionals to Objective-C, so it falls back on boxing it with `_SwiftValue` – which isn't castable to `NSString`. See [this Q&A](http://stackoverflow.com/questions/39033194/anyobject-not-working-in-xcode8-beta6) for more info about `_SwiftValue`. — Hamish, Sep 17 '16 at 08:58

score 2 · Answer 1 · edited May 23 '17 at 12:16

The bad point resides here:

anyObj["ft_of_time"] as AnyObject

(Please check this.)

If you are sure anyObj["ft_of_time"] is of type NSString, simply use as!, else you should use Optional binding:

if let rawFt_of_time = anyObj["ft_of_time"] as? NSString {
    let ft_of_time = Utils.convert_string(string: rawFt_of_time.substring(to: 5) as NSString)
    //Use ft_of_time here...
}

Do not use as AnyObject to silence the compiler...

vadian · Accepted Answer · 2019-04-15T11:47:30.050

1

The error reason is that Swift 3 AnyObject? cannot be cast directly to Foundation NSString.

You could write

let ft_of_time = ((anyObj["ft_of_time"] as! String as NSString).substring(to: 5) as NSString)

But I recommend to replace the entire line with

let ftOfTime = anyObj["ft_of_time"] as! String
let ft_of_time = ftOfTime.substring(to:ftOfTime.index(ftOfTime.startIndex, offsetBy: 5)) as NSString

It does the same but it uses native Swift API. Except the final cast to NSString (if needed at all) there is no type casting back and forth.

edited Apr 15 '19 at 11:47

answered Sep 17 '16 at 08:46

vadian

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the code was working with swift 2 but after converting to swift 3 it stopped working – Amir_P Sep 17 '16 at 08:58
`NSString` is foundation but `String` isn't? then what is `String`? – mfaani Sep 17 '16 at 13:20
`String` is a native Swift type, a struct with value type semantics (unlike Foundation's `NSString` which is reference type). It's quite similar to `NSString` but has a few different functions. For compatibility `String` can be easily bridged to `NSString`. – vadian Sep 17 '16 at 14:02

score 0 · Answer 3 · answered Sep 17 '16 at 08:37

0

You can convert String to NSString like

let swiftString:String = "Swift style string"
let objCString:NSString = NSString(string:swiftString)

so first cast your string to nsstring properly then you can use methods of nsstring

answered Sep 17 '16 at 08:37

Ketan Parmar

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score -1 · Answer 4 · answered Aug 23 '18 at 05:57

-1

This problem (Could not cast value of type '_SwiftValue' to 'NSString') can be solved like this too:

    let price = "\(String(describing: single_product_dict.value(forKey: "total_price_format") ?? ""))"
    cell.lblPrice.text = price

answered Aug 23 '18 at 05:57

Shivam Tripathi

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Could not cast value of type '_SwiftValue' error

4 Answers4