In Swift 4, how can you get the string-representation of a data type stored in a variable of type 'Any'?

Question

What is the easiest way to get the string-representation of a value's data type if that value is stored in an 'Any' variable?

For instance, I'm debugging code that has this...

extension SomeClass : Mappable{

    static func map(value:Any) -> SomeClass{

        return Parse(value)

    }
}

I'm trying to figure out what data types are being passed through the function, but if I use type(of:) I keep getting 'Any' and not the value held in it.

extension SomeClass : Mappable{

    static func map(value:Any) -> SomeClass{

        let nameOfType = ??? <-- This is what I'm trying to figure out
        log(nameOfType)

        return Parse(value)

    }
}

I simply want to print the data type to the debug window, not do testing with is or as, etc. It's strictly for logging/debugging reasons.

`String.init(describing:value)`? You can override `description` (https://developer.apple.com/documentation/swift/string/2427941-init) if needed. — Larme, Dec 07 '17 at 19:21
No, that's a string representation of the *value*. I want the string representation of the *data type* *of* that value. — Mark A. Donohoe, Dec 07 '17 at 19:24
Do you mean this code snippet returns 'Any'? func map(value: Any) { print(type(of: value)) } let value = 67 map(value: value) — Dorukhan Arslan, Dec 07 '17 at 19:26
https://stackoverflow.com/a/41196105/1801544 then maybe some ideas? — Larme, Dec 07 '17 at 19:28
`print(type(of: value))` works fine for me in a playground...is this the exact code you're working with? — GetSwifty, Dec 07 '17 at 19:35
String if I pass a String, Int if I pass an Int, etc. I obviously don't have your whole class so it's just with a Test example — GetSwifty, Dec 07 '17 at 19:37
@MarqueIV I get 'Int' as expected. Therefore, I gave that example. — Dorukhan Arslan, Dec 07 '17 at 19:45

score 1 · Answer 1 · answered Dec 08 '17 at 19:02

Ok, I figured it out. It's a two-step process.

You have to:

Use type(of:) to get the type of the variable (as others have described)
Use String(describing:) to get the name of that type (that was the missing piece)

Here's an example...

let typeName = String(describing: type(of:value))

That's what I was after. Thanks for the other answers. Hope this helps!

score 0 · Answer 2 · answered Dec 07 '17 at 20:01

0

static func map(value:AnyObject) -> AnyClass{

    return value.classForCoder

}

Or

static func map(value:Any) -> AnyClass{

    return (value as AnyObject).classForCoder

}

answered Dec 07 '17 at 20:01

Santhosh R

1,518
2
10
14

This isn't what I'm after. Just like the other answer above, this changes the return type of the function. I'm trying to debug. I'm trying to log what's passed in. (I've updated the question to be more clear.) – Mark A. Donohoe Dec 08 '17 at 18:58

score 0 · Answer 3 · answered Dec 07 '17 at 20:10

0

In Swift 4 you can achieve that like this:

static func map(value: Any) -> Any.Type {
    return type(of: value)
}

answered Dec 07 '17 at 20:10

Mo Abdul-Hameed

6,030
2
23
36

This changes the return type of the function. I'm trying to debug what's being passed to an existing function, not change the function. Make sense? (I've updated the question to be more clear.) – Mark A. Donohoe Dec 08 '17 at 18:58

In Swift 4, how can you get the string-representation of a data type stored in a variable of type 'Any'?

3 Answers3