Swift introduces new ways to model data through value types like structs and enums. I’ll discuss my experiences rewriting the data model of the vector graphics app Sketch to use value trees. I’ll finish off pondering whether future data modelling frameworks could be based on value trees, rather than entities and relationships, and introduce the experimental open source project Impeller (https://github.com/mentalfaculty/impeller), which is a step in that direction. This talk was given at dotSwift 2017.

1. THE VALUE IN TREES
DREW MCCORMACK

5. SKETCH
PROBLEMS
▸ Edits during saves
▸ Edits during rendering
▸ Fragile undo

7. SNAPSHOT
Time

11. 1.02.0

13. VALUE TYPES
PROS
▸ Stack memory
▸ No reference counting
▸ Safe between threads
▸ No changes behind your back

14. struct Document {
var sections: [Section]
}
struct Section {
var paragraphs: [Paragraph]
}
struct Paragraph {
var style: ParagraphStyle
var content: String
}

15. class ViewController {
var document: Document {
didSet {
self.reloadViews()
}
}
}
let c = ViewController()
c.document.sections[0].paragraphs[0].style = ...

16. 1.02.0

18. CAN I HAVE A VALUE STORE
FOR XMAS?

19. …AND CAN I HAVE IT SYNC?

20. DISTRIBUTED VALUE STORE (DVS)

21. DISTRIBUTED VALUE STORE (DVS)
Repository

22. DISTRIBUTED VALUE STORE (DVS)
struct Person {
var name = "Bob"
var age = 32
var tags = ["clean", "smart"]
}

23. DISTRIBUTED VALUE STORE (DVS)
struct Person {
var name = "Bob"
var age = 32
var tags = ["clean", "smart"]
}
CloudKit Repository

24. DISTRIBUTED VALUE STORE (DVS)
struct Person {
var name = "Bob"
var age = 32
var tags = ["clean", "smart"]
}

25. github.com/mentalfaculty/impeller

26. import Impeller
struct Person: Storable {
static let storedType = "Person"
var metadata = Metadata()
var name = "No Name"
var age: Int? = nil
...

27. init?(readingFrom repository:ReadRepository) {
name = repository.read("name")!
age = repository.read(optionalFor:"age")!
}
func write(in repository:WriteRepository) {
repository.write(name, for: "name")
repository.write(age, for: "age")
}

29. ATTRIBUTION
IMAGES
▸ Sketch Logo
▸ https://www.sketchappsources.com/free-source/2332-new-sketch-vector-icon.html
▸ Bamboo Forest
▸ https://www.pexels.com/photo/nature-forest-trees-bamboo-5091/
▸ Redwood Forest
▸ https://commons.wikimedia.org/wiki/File:Sequoia_sempervirens_Big_Basin_Redwoods_State_Park_4.jpg
▸ Notes
▸ http://www.cooperazionetrentina.it/Giovani/Iniziative/Iniziative-2015/I-giovani-e-la-cooperazione-che-cambia-7-edizione
▸ Crop Circles
▸ https://commons.wikimedia.org/wiki/File:CropCircleW.jpg
▸ iPhone
▸ https://commons.wikimedia.org/wiki/File:IPhone_with_icons.svg
▸ Database Icon
▸ https://pixabay.com/en/database-diagram-data-storage-disk-29954/
▸ Jedward
▸ https://www.flickr.com/photos/chiropractic/6849052778
▸ No cycling
▸ https://commons.wikimedia.org/wiki/File:Uruguay_Road_Sign_Bicycles_Only.svg
▸ Planting
▸ https://www.flickr.com/photos/usfsregion5/3598029211