How to Compare AnyObject Is or not?

Question

I am writing below function to return value based on data objet that I passed to this method.

If we get data null I am trying to return "-" otherwise If I get any valid response I am returning value..

private func checkDataForValue(data: Optional<AnyObject>) -> String {
    if let value = data {
        let value1: AnyObject = //have to check <Null>
        if value === value1 {
            return "-"
        }
        return "\(value)"
    } else {
        return "-"
    }
}

My question How to compare null value here ..

The `if let` is already check to see if `data` is `nil` or not. `value` can't be `nil`. — rmaddy, Aug 27 '18 at 17:02
`AnyObject` can't be null. Only optionals can be null. Except for perhaps `NSNull`, I don't know much about how that bridges into swift from ObjC — Alexander, Aug 27 '18 at 17:02
Thanks rmaddy ..but here value coming as and it's coming into the loop not going out..! — tp2376, Aug 27 '18 at 17:09
Possibly helpful: https://stackoverflow.com/questions/29954806/how-to-check-if-nsmutablearray-element-is-nsnull-or-anyobject — Martin R, Aug 27 '18 at 18:58

rmaddy · Accepted Answer · 2018-08-28T15:56:45.590

1

Most likely you are looking to compare value with NSNull.

You can update your code as follows:

private func checkDataForValue(data: Any?) -> String {
    if let value = data {
        if value is NSNull != nil {
            return "-"
        } else if (value as? String)?.lowercased() == "<null>" {
            return "-"
        } else {
            return "\(value)"
        }
    } else {
        return "-"
    }
}

edited Aug 28 '18 at 15:56

answered Aug 27 '18 at 18:41

rmaddy

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Why don't you use `value is NSNull` instead of `value as? NSNull != nil` ? – OOPer Aug 27 '18 at 18:52
@OOPer Because sometimes you forget the obvious. :) That would be simpler. Thanks. – rmaddy Aug 27 '18 at 20:02
Thanks rmaddy, Here I am trying to get value and "value as? NSNull == nil ? "\(value)" : "-" " Is giving me value with optional character(optional(8))..Any ideas how to remove that optional char .. – tp2376 Aug 27 '18 at 20:09
I want value if it's not nill and if it's nill "-" but above logic is not giving "-" when it's nill. – tp2376 Aug 27 '18 at 20:34
If `data` is `nil` then you get `-` from the `else`. If `data` is not `nil` then `value is compared against `NSNull`. If `value` is an instance of `NSNull`, you get `-`, otherwise you get a string representation of `value`. If you are still getting `` then `data` isn't `nil` nor is it an instance of `NSNull`. It must be a `String` with the value ``. After the `if let`, before the `return`, add `print(type(of: value))`. Update your question with the result of that line. – rmaddy Aug 27 '18 at 20:40
print(type(of: value)) it will have Int and String objets.. If data is nill it's not going into else loop it's still going into if loop..! – tp2376 Aug 27 '18 at 21:14
You need to actually add that line and run your code. Tell is the output of that `print` when you are getting `` as a result. – rmaddy Aug 27 '18 at 21:17
I added that line and the value is nil but it's going into if loop, when I print that I am getting Optional or Optional. – tp2376 Aug 28 '18 at 13:37
Sounds like your data contains the literal string "" Again, telling us how you're getting the original data *might* help us figure out what's going on. But we still don't know exactly what @rmaddy's fragment prints WHEN you get the "" result. – David Berry Aug 28 '18 at 15:29
@tarun Try my update. This deals with the literal string `""`. And there's no loop here. Instead of saying the "if loop", say the "if block" vs "else block". – rmaddy Aug 28 '18 at 15:57
@rmaddy Yes It did .. Thank u so much – tp2376 Aug 31 '18 at 13:53

David Berry · Answer 2 · 2018-08-28T16:01:33.847

0

I'd take advantage of the power of switch cases and go with:

private func checkDataForValue(data: Any?) -> String {
    switch data {
    case .none, .some(is NSNull):       return "-"
    case .some(let value as String):    return value == "<null>" ? "-" : value
    case .some(let value):              return "\(value)"
    }
}

edited Aug 28 '18 at 16:01

answered Aug 27 '18 at 20:52

David Berry

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As @rmaddy suggests, try adding `print(type(of: data))` to see what it is that you're really getting then. It may just be a string containing "" and not an `NSNull` issue at all. It also might help to have some context around your question and the usage of `checkDataForValue` – David Berry Aug 27 '18 at 21:14
If I add print(type(of: data)) in above code I am getting and It's not a NSNull it is String though.. – tp2376 Aug 28 '18 at 14:01
Updated the chunk above to cover the string literal "" case. – David Berry Aug 28 '18 at 15:57

How to Compare AnyObject Is or not?

2 Answers2