How do I convert NSDictionary to Dictionary?

Question

I have already updated to XCode 8 and now I need to convert my code from Swift 2 to Swift 3.

Before, when I want to convert NSDictionary to Dictionary, I just wrote the following:

let post_paramsValue = post_params as? Dictionary<String,AnyObject?>

where post_params is NSDictionary.

But now with Swift 3, I am receiving this error:

NSDictionary is not convertible to Dictionary

Why? What's changed?

Edit 1

I've also tried the following:

let post_paramsValue = post_params as Dictionary<String,Any>

But that gives this error:

Edit 2

I've also tried the following:

let post_paramsValue =  post_params as Dictionary<String,Any>

Where I declare NSDictionary instead of NSDictionary!, but it doesn't work; I got this error:

Edit 3

I've also tried the following:

let post_paramsValue =  post_params as Dictionary<String,Any>!

But I received this error:

tried this ? http://stackoverflow.com/questions/31765875/casting-nsdictionary-as-dictionary-swift — Umair Afzal, Nov 01 '16 at 10:57
@UmairAfzal thank you for your comment, but why i need to go through dictionary using loop , this is not convenient , why apple need to make things harder ? — david, Nov 01 '16 at 10:58
@UmairAfzal i didn't try it ,i am pretty sure that it will work but this is not convenient . i need to do it with the best way. thanks — david, Nov 01 '16 at 11:13

vadian · Accepted Answer · 2019-11-04T15:14:07.657

25

NSDictionary in Objective-C has always non-optional values.
AnyObject has become Any in Swift 3.
Considering the first two "rules" NSDictionary can be bridge cast to Dictionary

let post_paramsValue = post_params as Dictionary<String,Any>

If the source NSDictionary is an optional you might use as Dictionary<String,Any>? or as? Dictionary<String,Any> or as! Dictionary<String,Any> or as Dictionary<String,Any>! depending on the actual type of the NSDictionary

edited Nov 04 '19 at 15:14

answered Nov 01 '16 at 10:53

vadian

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thank you for your answer, but i've tried this before and it didn't work , i've edit the question – david Nov 01 '16 at 10:56
Then use the forced cast operator `as!` since the source dictionary is optional. – vadian Nov 01 '16 at 10:58
thanks again, why i can't use this : let post_paramsValue = post_params as Dictionary! – david Nov 01 '16 at 11:01
You can use that, too – vadian Nov 01 '16 at 11:02
no it shows error message, one minute i will add the screen shot to my answer – david Nov 01 '16 at 11:04
1

Consider to declare the `NSDictionary` as non-optional. – vadian Nov 01 '16 at 11:05
it also doesn't work , i will add two screen shots one minute please – david Nov 01 '16 at 11:07
i've edited my question with all your suggestions , please have a look & let me what do you think, thanks – david Nov 01 '16 at 11:12
Have you tried the suggested `as!` (with exclamation mark)? I'd avoid to use `NSDictionary` in Swift at all unless you have no choice. – vadian Nov 01 '16 at 11:13
i did this "let post_paramsValue = post_params as? Dictionary " just to avoid run time exception and it works. but why the other bridge suggestion doesn't work – david Nov 01 '16 at 11:18

score 3 · Answer 2 · edited Aug 23 '18 at 17:39

For those who have a problem with NSDictionary, simply use this extension:

Swift 3.0

extension NSDictionary {
    var swiftDictionary: Dictionary<String, Any> {
        var swiftDictionary = Dictionary<String, Any>()

        for key : Any in self.allKeys {
            let stringKey = key as! String
            if let keyValue = self.value(forKey: stringKey){
                swiftDictionary[stringKey] = keyValue
            }
        }

        return swiftDictionary
    }
}

score 0 · Answer 3 · answered Mar 24 '20 at 12:05

0

You just need to declare the NSDictionary properly in objc

For example: NSDictionary<NSString *, NSString*> gets translated automatically to [String: String] in swift interfaces

answered Mar 24 '20 at 12:05

Exception

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How do I convert NSDictionary to Dictionary?

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3 Answers3

Swift 3.0