Struct vs Class in Swift

This topic it is a comparison between structs and classes in Swift, it also presents why you should adopt structs, because coming from Objective-C you are tended to use classes all over the code without having any benefit of Swift features.

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1. STRUCT vs CLASS Laurentiu Ungur, iOS Developer @P3-Digital Services
2. Why I should use a struct instead of a class ?
3. 1. POWERFUL
4. PROBLEM WITH SUBCLASSING ?
5. struct Vehicle { let model: String let price: Double }
6. enum VehicleType { case car(licensePlate: String) case bicycle(chainRings: Int) }
7. struct Vehicle { let model: String let price: Double let type: VehicleType }
8. let car = Vehicle(model: “X”, price: 200, type: .car(licensePlate: “CJ”)) let bicycle = Vehicle(model: “A”, price: 10, type: .bicycle(chainRings: 100))
9. 2. VALUE SEMANTICS
10. 3. AUTOMATIC INITIALIZER
11. struct Car { let brand: String let model: String let price: Double }
12. struct Car { let brand: String let model: String let price: Double init(brand: String, model: String, price: Double) { self.brand = brand self.model = model self.price = price } } let myCar = Car(brand: “Tesla”, model: “S”, price: 100)
13. struct Car { let brand: String let model: String let price: Double } let myCar = Car(brand: “Tesla”, model: “S”, price: 100)
14. 4. SPEED
15. 40x Faster Swift 1 github.com/knguyen2708/StructVsClassPerformance
16. 37 000 000x Faster Swift 2 - Whole Module Optimization github.com/knguyen2708/StructVsClassPerformance
17. 14 000 000x Faster Swift 3 - Whole Module Optimization github.com/knguyen2708/StructVsClassPerformance
18. Use final keyword
19. unsplash.com/collections/328902/cow
20. COW (Copy-On-Write)
21. let a = [1, 2, 3] var b = a // not copied b.append(4) // now it’s copied
22. When I should use a struct ? • The data will be used in code across multiple threads
23. When I should use a struct ? • The data will be used in code across multiple threads • Copies should have independent state
24. When I should use a struct ? • The data will be used in code across multiple threads • Copies should have independent state • Encapsulates a few relatively simply data values
25. When I should use a class ? • You want to create shared, mutable state
26. When I should use a class ? • You want to create shared, mutable state • You want to create complex frameworks like Cocoa or Cocoa Touch
27. Still undecided ? Design with struct as default, fallback to class if it’s really needed.
28. THANKS !