DIY your own Combine framework

Transcript

1. DIY your own Combine framework Basic Functional Reactive Programming concepts Li-Heng Hsu 許立衡 @ iPlayground 2019
2. – Apple documentation "The Combine framework provides a declarative Swift API for processing values over time."
4. Concepts • Builder pattern • map(_:) method
5. Builder pattern • For constructing instances • Like initializer, factory method… 1. Create a builder struct 2. Store construction info in it 3. Call its build() method to construct a product
6. URLComponents URL builder
7. Combine Subscription builder
8. Builder pattern Combine Builder Publisher Construction info Operator build() Subscriber Product Subscription Roles
9. CombineDIY.swift
10. map(_:) method • There are different worlds in code • World of Uncertainty, World of Plurality, World of Erroneous... • Instances in these worlds can't be manipulated normally
11. Optional World of Uncertainty
12. World of Uncertainty Cat? (Cat) -> Double (Cat?) -> Double? map(_:)
14. Imperative Functional Metaphor Unwrap values Stack operations Optional if let x = x { /* ... */ } x.map { x in /* ... */ } Collection for i in x { /* ... */ } x.forEach { i in /* ... */ } Result if case .success(let x) = result { /* ... */ } result.map { x in /* ... */ }
15. World of Plurality [Cat] (Cat) -> Double ([Cat]) -> [Double] map(_:)
16. World of Temporality Publisher<Cat> (Cat) -> Double (Publisher<Cat>) ->
 Publisher<Double> map(_:)
17. DIY map(_:)
18. Feedback Come find me! Twitter: @lihenghsu