Key-Value Coding (KVC) with Array/Dictionary in Swift

Question

Is it possible to key-value code (KVC) with native Swift data structures such as Array and Dictionary? Key-Value coding is still available for NSFoundation structures within Swift, just like in Objective C.

For example, this is valid:

var nsarray: NSArray = NSArray()
// Fill the array with objects
var array: NSArray = nsarray.valueForKeyPath("key.path")

But this is invalid:

var swiftarray: Array = []
// Fill the array with objects
var array = swiftarray.valueForKeyPath("key.path") // Invalid, produces a compile-time error

Check out this post by Matt Long: http://www.cimgf.com/2014/11/05/swift-and-valueforkeypath-you-cant-keep-a-good-api-down/ — Drew C, Jun 30 '15 at 16:38

score 11 · Accepted Answer · answered Oct 14 '14 at 18:14

It seems that KVC on native Swift objects is just not supported. Here's the most elegant workaround I've found:

var swiftarray: Array = []
// Fill the array with objects
var array: NSArray = (swiftarray as NSArray).valueForKeyPath("key.path") as NSArray

score 8 · Answer 2 · answered Jun 07 '15 at 11:52

8

I've found this:

var array = swiftarray.map({$0["key.path"]! as ObjectType})

answered Jun 07 '15 at 11:52

Phoenix

181
3
13

score 2 · Answer 3 · answered May 17 '16 at 12:29

2

you can do the following:

let items : Array<String> = (myArray as AnyObject).valueForKeyPath("name") as! Array<String>

answered May 17 '16 at 12:29

Grégoire Aubin

163
8

score 1 · Answer 4 · answered Feb 04 '19 at 15:06

1

How about this:

let names = array.map { $0.name }

Instead of using key paths you can directly refer to property or method.

answered Feb 04 '19 at 15:06

vahotm

379
5
16

Key-Value Coding (KVC) with Array/Dictionary in Swift

4 Answers4

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