How to use Dictionary.compactMapValues

Transcript

1. How to use Dictionary.compactMapValues potatotips #55 Daiki Matsudate / @d_date

2. Daiki Matsudate @d_date

3. https://peaks.cc/iOS_architecture

4. IUUQTZBLJSJOHPCPPUIQNJUFNT

5. Dictionary .compactMapValues

6. extension Dictionary { public func compactMapValues<T>(_ transform: (Value) throws ->

   T?) rethrows -> [Key: T] { return try self.reduce(into: [Key: T](), { (result, x) in if let value = try transform(x.value) { result[x.key] = value } }) } } Available in Swift 5

7. Use Cases

8. let d1 = ["a": "1", "b": "2", "c": nil] d1.filter({

   $0.value != nil}).mapValues({ $0! }) // ["b": "2", "a": "1"]

9. ["a": "1", "b": nil, "c": “3”].compactMapValues({ $0 }) // ["a"

   : 1, "c" : 3]

10. var object = { 'a': 1, 'b': null, 'c': 3

    }; _.omitBy(object, _.isNil); // => { 'a': 1, 'c': 3 } DG
    @PNJU#Z

11. let d = ["a": "1", "b": "2", "c": "three"] d.mapValues(Int.init).filter({

    $0.value != nil}).mapValues({ $0! })

12. extension Dictionary { public func compactMapValues<T>(_ transform: (Value) throws ->

    T?) rethrows -> [Key: T] { return try self.reduce(into: [Key: T](), { (result, x) in if let value = try transform(x.value) { result[x.key] = value } }) } }

13. let d = ["a": "1", "b": "2", "c": "three"] d.compactMapValues(Int.init)

    // ["b": 2, "a": 1]
14. None

15. • Daiki Matsudate / @d_date Available in Swift 5

16. Make our Swift better 09/05/2018 try! Swift NYC Daiki Matsudate

    / @d_date
17. None

18. • compactMapValues is available in Swift 5 • compactMapValues can

    transform and unwrap dictionary • Let’s try to contribute to Swift lang Recap
19. None