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

Daiki Matsudate @d_date

https://peaks.cc/iOS_architecture

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Dictionary .compactMapValues

extension Dictionary { public func compactMapValues(_ 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

Use Cases

let d1 = ["a": "1", "b": "2", "c": nil] d1.filter({ $0.value != nil}).mapValues({ $0! }) // ["b": "2", "a": "1"]

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

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

let d = ["a": "1", "b": "2", "c": "three"] d.mapValues(Int.init).filter({ $0.value != nil}).mapValues({ $0! })

extension Dictionary { public func compactMapValues(_ 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 } }) } }

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

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• Daiki Matsudate / @d_date Available in Swift 5

Make our Swift better 09/05/2018 try! Swift NYC Daiki Matsudate / @d_date

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• compactMapValues is available in Swift 5 • compactMapValues can transform and unwrap dictionary • Let’s try to contribute to Swift lang Recap

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