Swift + GraphQL

Interfacing with GraphQL in Swift
Sommer Panage • @sommer
1 — Sommer Panage • @sommer • Swift Summit 2016

Hello!

What is GraphQL?

The GraphQL Schema
type User {
name: String!
id: Int!
email: String
twitter: String
}

Instead of hitting a REST endpoint like...
https://mybackend.com/api/user?id=1

I write a query like...
{
user(id: 1) {
name
email
twitter
}
}
And send it to my GraphQL endpoint
https://mybackend.com/graphql

And I get back a JSON response like...
{
"data": {
"name": "Sommer Panage",
"email": "sommer@panage.org",
"twitter": "@sommer"
}
}

Why is GraphQL such a
big deal for mobile?

Let's write an app

In a REST world, we'd hit this endpoint:
http://swapi.co/api/people/1/
And we'd get back...

{
"name": "Luke Skywalker",
"height": "1.72 m",
"mass": "77 Kg",
"hair_color": "Blond",
"skin_color": "Caucasian",
"eye_color": "Blue",
"birth_year": "19 BBY",
"gender": "Male",
"homeworld": "http://swapi.co/api/planets/1/",
"films": [
"http://swapi.co/api/films/1/",
"http://swapi.co/api/films/3/"
],
"species": [
"http://swapi.co/api/species/1/"
],
"vehicles": [
"http://swapi.co/api/vehicles/14/",
"http://swapi.co/api/vehicles/30/"
],
"starships": [
"http://swapi.co/api/starships/12/",
"http://swapi.co/api/starships/22/"
],
"created": "2014-12-09T13:50:51.644000Z",
"edited": "2014-12-10T13:52:43.172000Z",
"url": "http://swapi.co/api/people/1/",
"image_url": "http://static.srcdn.com/wp-content/uploads/luke-skywalker-star-wars-a-new-hope.jpg"
}

And then...we'd make two more calls to...
http://swapi.co/api/starships/12/
and
http://swapi.co/api/starships/22/

{
"name": "X-wing",
"model": "T-65 X-wing",
"manufacturer": "Incom Corporation",
"cost_in_credits": "149999",
"length": "12.5",
"max_atmosphering_speed": "1050",
"crew": "1",
"passengers": "0",
"cargo_capacity": "110",
"consumables": "1 week",
"hyperdrive_rating": "1.0",
"MGLT": "100",
"starship_class": "Starfighter",
"pilots": [
"http://swapi.co/api/people/1/",
"http://swapi.co/api/people/19/"
],
"films": [
],
"created": "2014-12-12T11:19:05.340000Z",
"edited": "2014-12-22T17:35:44.491233Z",
"url": "http://swapi.co/api/starships/12/"
}

{
"name": "Imperial shuttle",
"model": "Lambda-class T-4a shuttle",
"manufacturer": "Sienar Fleet Systems",
"cost_in_credits": "240000",
"length": "20",
"max_atmosphering_speed": "850",
"crew": "6",
"passengers": "20",
"cargo_capacity": "80000",
"consumables": "2 months",
"hyperdrive_rating": "1.0",
"MGLT": "50",
"starship_class": "Armed government transport",
"pilots": [
"http://swapi.co/api/people/14/"
],
"films": [
],
"created": "2014-12-15T13:04:47.235000Z",
"edited": "2014-12-22T17:35:44.795405Z",
"url": "http://swapi.co/api/starships/22/"
}

That's 3 calls and a whole lot of data for 1 little VC

Now in GraphQL, instead we'd write the following query:
{
person(personID: 1) {
name,
height,
mass,
hairColor,
eyeColor,
imageURL,
starshipConnection {
edges {
node {
name
}
}
}
}
}

And, I'd get back exactly what I wanted!
{
"data": {
"person": {
"name": "Luke Skywalker",
"height": 172,
"mass": 77,
"hairColor": "blond",
"eyeColor": "blue",
"imageURL": "http://static.srcdn.com/wp-content/uploads/luke-skywalker-star-wars-a-new-hope.jpg",
"starshipConnection": {
"edges": [
{
"node": {
"name": "X-wing"
}
},
{
"node": {
"name": "Imperial shuttle"
}
}
]
}
}
}
}

So, why is GraphQL such a big deal for mobile?
1. Ask and ye shall receive!
2. Fewer round trips!
3. Less client logic around data!

Wait just a minute...

Our Star Wars Character model
struct SWCharacter {
let name: String
let heightInCm: Int
let massInKg: Int
let hairColorDescriptor: String
let skinColorDescriptor: String
let eyeColorDescriptor: String
let birthYear: StarWarsUniverse.Year
let gender: StarWarsUniverse.Gender
let homeworld: StarWarsUniverse.Planet
let films: [SWFilm]
let species: [StarWarsUniverse.Species]
let vehicles: [StarWarsUniverse.Vehicle]
let starships: [StarWarsUniverse.Starship]
let imageURL: URL?
}

Our Star Wars Character model
let name: String?
let heightInCm: Int?
let massInKg: Int?
let hairColorDescriptor: String?
let skinColorDescriptor: String?
let birthYear: StarWarsUniverse.Year?
let gender: StarWarsUniverse.Gender?
let homeworld: StarWarsUniverse.Planet?
let films: [SWFilm]?
let species: [StarWarsUniverse.Species]?
let vehicles: [StarWarsUniverse.Vehicle]?
let starships: [StarWarsUniverse.Starship]?
let imageURL: URL?
}

Swift, No!!!!
let name: String?
let heightInCm: Int?
let massInKg: Int?
let hairColorDescriptor: String?
let skinColorDescriptor: String?
let birthYear: StarWarsUniverse.Year?
let gender: StarWarsUniverse.Gender?
let homeworld: StarWarsUniverse.Planet?
let films: [SWFilm]?
let species: [StarWarsUniverse.Species]?
let vehicles: [StarWarsUniverse.Vehicle]?
let starships: [StarWarsUniverse.Starship]?
let imageURL: URL?
}

Let's model the data how we want it, not how it is
→ 1 View Controller
→ 1 Query
→ 1 Data Model

query AllCharacters {
allPeople {
edges {
node {
id
name
homeworld {
name
}
}
}
}
}

struct AllCharactersData {
let people: [Person]
struct Person {
let id: String
let name: String
let homeworld: Homeworld
struct Homeworld {
let name: String
}
}
}

query Character($id: ID) {
person (id: $id) {
id
height,
mass,
hairColor,
eyeColor,
imageURL,
starshipConnection {
edges {
node {
name
}
}
}
}
}

struct CharacterData {
struct Person {
let id: String
let height: Int
let mass: Int
let hairColor: String
let eyeColor: String
let imageURL: URL?
let starshipConnect: [Starship]
struct Starship {
let name: String
}
}
}

By having query / view-
data based models, we
no longer need optionals
everywhere!

But our parsing code still looks like...
let parsedData = try JSONSerialization.jsonObject(with: data, options: []) as! [String: Any]
self.id = parsedData["id"] as! String
self.name = parsedData["name"] as! String
self.homeworld = Homeworld(dict: parsedData["homeworld"] as! [String : Any])
Ugh!

Code Gen!

Apollo's iOS GraphQL Client for Swift
→ Compile-time safety
→ Inline validation errors for GraphQL
→ No wasted cycles on query-gen

What about...?

Versioning
→ "Version-Free"
→ Easy to test for backwards compatability

Caching

Simple Caching
Query-based, not object based

Advanced Caching
Flattened results, id-record mapped

Aren't you supposed to
use GraphQL with React
Native?

GraphQL + Swift
-> GraphQL shines on mobile
-> Swift gives us types and compile time safety
-> React Native is new and exciting, but that comes
with challenges too

In
Conclusion...

Pros to GraphQL + Swift
→ Fewer requests for data
→ Getting the exact data you need
→ Code gen -> no janky parsing code
→ Models that are reﬂective of your views
→ A strongly typed backend schema

Cons to GraphQL + Swift
→ Not a lot of tooling yet
→ Best practices still emerging
→ Poorly deﬁned schema becomes a big client
problem
→ Not as good for endpoints requiring heavy logic

tldr: It's worth
it!

Check out
→ Apollo iOS Client: Documentation and info on
Apollo's awesome Swift iOS GraphQL client
→ 5 beneﬁts of static GraphQL Queries: Blog post
from Apollo
→ Bringing GraphQL to iOS: Blog post from Apollo
→ GraphQL First: A better way to build modern apps:
Blog post from Apollo

Check out...con’t
→ GraphQL for mobile: Blog post from Artsy
→ Relay: Thinking in GraphQL: Post from FB on
Caching

Thank you!!
Come ask me questions about GraphQL + Swift
or about Accessibility!

Credits
Images
GediminasTurbo Baltaduonis, Danil Polshin, Apple,
Facebook, Apollo, Lucasﬁlm
General
Chorus Fitness, Apollo, Facebook

Swift + GraphQL

More Related Content

What's hot

Viewers also liked

Similar to Swift + GraphQL

Recently uploaded

Swift + GraphQL