ShortHands¶

It is always easier to forget which shorthands | higher order functions are available and sometimes you need a refresher in terms of an example with input and output.

Map¶

RxSwift Map map

FlatMap¶

RxSwift FlatMap flatMap

CompactMap¶

Removes the nil values when working with sequence variables.

let optionalArr = [1, nil, 3, 4, 6, nil, nil, 42]
let nonEmptyArr = arr.compactMap()
print(nonEmptyArr) // 1,3,4,6,42

Filter¶

Whatever returns a true boolean value would get filtered appropriately. Filter works on sequence variables types like Set, Array, Dictionary.

// Even Odd example

let arr = [1, 2, 3, 4]
let evens = arr.filter { $0 % 2 == 0 }
print(evens)

// Struct filter

struct FieldFilter {
    let hasDynamicRecordId: Bool
    let name: String
}

let arrFields = [
    FieldFilter(hasDynamicRecordId: true, name: "Test 1"),
    FieldFilter(hasDynamicRecordId: false, name: "Test 2"),
    FieldFilter(hasDynamicRecordId: false, name: "Test 3"),
    FieldFilter(hasDynamicRecordId: true, name: "Test 4"),
    FieldFilter(hasDynamicRecordId: true, name: "Test 5"),
]

let dynamicRecordFields = arrFields.filter { $0.hasDynamicRecordId }
print(dynamicRecordFields)

Checking conditions in Map¶

If you want to check specific condition in an array with short hand - higher order functions you could utilize allSatisfy condition to check a specific predicate in all the elements of an array.

struct Feature { 
    let showView: Bool
    let showNotification: Bool
    let name: String               
}
let features: [Feature] = [
    Feature(showView: true  , showNotification: false , name: "Kay"),
    Feature(showView: true  , showNotification: true , name: "Nay"),
    Feature(showView: true  , showNotification: false , name: "Say")
]

let featureShowViewSatisfy = features
                                .map(\.showView)
                                .allSatisfy{ $0 == true }

print(featureShowViewSatisfy) // prints true Bool
myCustomView.isVisible = featureShowViewSatisfy

Collection Cheat sheet¶

KeyPaths in higher order functions¶

keypaths

Note¶

Have added appropriate RxSwift implementations of map, flatMap, compactMap as well in RxSwift

Resources¶

Apple Docs

swiftbysundell map basics