Convert NSDictionary to Swift Dictionary

Question

Now I know that when swift compiles it just makes a NSDictionary, but the NSDictionary and Swift dictionaries have different syntax. Is there a way (through a loop or something) to convert a NSDictionary to a swift dictionary of the same type for <key, value>?

OR

Is there a way to convert this to a Swift dictionary instead of NSDictionary?

let jsonDict = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: &error) as NSDictionary

under the hood the _Swift_ `Dictionary` is literally an _Obj-C_ `NSMutableDictionary`, you can bridge them toll-free. — holex, Jul 04 '14 at 08:31

score 28 · Answer 1 · answered Aug 29 '14 at 09:29

28

use:

let jsonDic = NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers, error: &error) as Dictionary<String, AnyObject>;

answered Aug 29 '14 at 09:29

Arno van Lieshout

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For some reason, that didn't work for me. What worked for me was `let b = d as [NSObject:AnyObject]` – Mazyod Nov 20 '14 at 15:27
For SWIFT 3 you can use JSONSerialization. – Efren Jun 05 '17 at 02:29

score 4 · Answer 2 · edited Mar 02 '15 at 02:27

4

I found answer from http://www.swift-studies.com/blog/2014/6/6/loading-a-swift-dictionary-from-a-plist-file

var swiftDict : Dictionary<String,AnyObject!> = Dictionary<String,AnyObject!>()
for key : AnyObject in ocDictionary.allKeys {
    let stringKey = key as String 
    if let keyValue = ocDictionary.valueForKey(stringKey){
        swiftDict[stringKey] = keyValue
    }
}

edited Mar 02 '15 at 02:27

Leo Dabus

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answered Mar 02 '15 at 02:07

Yang

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Maybe in some very specific cases that may pay off, but I don't think that the overhead in memory, cpu and battery use of making a shallow copy of the NSDictionary has any real advantage. Since you can use an NSDictionary as a regular Dictionary the difference is almost non existent. – ncerezo Jun 24 '15 at 22:08

score 3 · Answer 3 · answered Jul 04 '14 at 08:07

3

NSDictionary and Dictionary are pretty much interchangeable. So there's no need to, but yes you can:

let jsonDict = (NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: &error) as NSDictionary) as Dictionary

answered Jul 04 '14 at 08:07

Oxcug

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Are they what? Interchangeable with their counterparts? Yes. – Oxcug Jul 29 '14 at 23:02
I keep having to type out `as NSString` everywhere though and ti doesn't like `as String`. Maybe this is because I'm defining `jsonDict : [[String:AnyObject]]`? – Chet Jul 29 '14 at 23:12
I believe it is, when going from AnyObject to anything, you have to cast it. – Oxcug Jul 30 '14 at 00:06
Beware bridging if NSDictionary to Dictionary is not toll free. – I make my mark Mar 31 '20 at 11:20

Convert NSDictionary to Swift Dictionary

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