This is the presentation I made at NSLondon meetup in may 2023. Learn how to structure a full-stack mobile app using Swift and a Serverless REST API. The talk covers the fundamentals of serverless application based on APIGateway, Lambda and DynamoDB and provide a quick start guide for developing a Serverless REST API with Breeze, a Swift package developed specifically for this purpose.

1. SERVERLESS IN SWIFT LIKE A BREEZE
ANDREA SCUDERI
SENIOR IOS ENGINEER @ JUST EAT TAKEAWAY
NSLondon
2023.2

2. AGENDA
▸ Demo App with Serverless
▸ App & Serverless Architecture
▸ Code Structure
▸ Code Generation
▸ Deployment
▸ Why Serverless, Why Swift? Why Breeze?

3. FULL STACK SWIFT

4. DEMO APP
GITHUB.COM/SWIFT-SPRINTER/BREEZEDEMOAPP
▸ SwiftUI
▸ Apple Sign In
▸ Serverless API in Swift
▸ CRUD (Create, Read, Update, Delete)

5. DEMO APP
DATA MODEL
public struct Form: Codable {
public var key: String
public let name: String
public let fields: [Field]
public var createdAt: String?
public var updatedAt: String?
public init(key: String,
name: String,
fields: [Field],
createdAt: String? = nil,
updatedAt: String? = nil) {
self.key = key
self.name = name
self.fields = fields
self.createdAt = createdAt
self.updatedAt = updatedAt
}
enum CodingKeys: String, CodingKey {
case key = "formKey"
case name
case fields
case createdAt
case updatedAt
}
}
public struct Field: Codable {
public let question: String
public let answer: String?
public let choices: [String]?
public let selected: [String]?
public let type: FieldType
public init(question: String,
answer: String? = nil,
choices: [String]? = nil,
selected: [String]? = nil,
type: FieldType) {
self.question = question
self.answer = answer
self.choices = choices
self.selected = selected
self.type = type
}
}
public enum FieldType: String, Codable {
case text
case option
case multiOption
}

6. SERVERLESS NO-SQL DB
AWS DYNAMODB
{
"formKey": {
"S": "114800A1-162F-4877-81BC-96E9A42E6559"
},
"createdAt": {
"S": "2023-05-06T08:31:37.866Z"
},
"fields": {
"L": [
{
"M": {
"choices": {
"L": [
{
"S": "Cost savings 💰 "
},
{
"S": "Performance ⚡ "
},
{
"S": "Scalability 🚀 "
},
{
"S": "Infrastructure as a Code 💨 "
}
]
},
"question": {
"S": "What is the main benefit of Serverless computing?"
},
"selected": {
"L": [
{
"S": "Cost savings 💰 "
},
{
"S": "Performance ⚡ "
},
{
"S": "Infrastructure as a Code 💨 "
},
{
"S": "Scalability 🚀 "
}
]
},
"type": {
"S": "multiOption"
}
}
},
{
"M": {

7. MOBILE & SERVERLESS
ARCHITECTURE
Mobile App API Gateway
HTTP/REST
+ (Bearer Token)
OAUTH 2.0
PROVIDER
JWT Token
https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-jwt-authorizer.html
Validation

8. SERVERLESS ARCHITECTURE

9. MOBILE & SERVERLESS
CODE ARCHITECTURE
BreezeLambdaAPIClient SharedModel
public struct Form: Codable {
public var key: String
public let name: String
public let fields: [Field]
public var createdAt: String?
public var updatedAt: String?
public init(key: String,
name: String,
fields: [Field],
createdAt: String? = nil,
updatedAt: String? = nil) {
self.key = key
self.name = name
self.fields = fields
self.createdAt = createdAt
self.updatedAt = updatedAt
}
enum CodingKeys: String, CodingKey {
case key = "formKey"
case name
case fields
case createdAt
case updatedAt
}
}
iOS - Swift
…
BreezeLambdaAPI BreezeDynamoDBService
SOTO

10. SHOW ME THE CODE!

11. APP API SERVICE
SERVICE-BASED BREEZE LAMBDA API CLIENT
struct FormService: FormServing {
private let apiClient: BreezeLambdaAPIClient<FeedbackForm>
private let session: SessionService
private var token: String? {
session.userSession?.jwtToken
}
init(session: SessionService) {
guard var env = try? APIEnvironment.dev() else {
fatalError("Invalid Environment")
}
env.logger = Logger()
self.session = session
self.apiClient = BreezeLambdaAPIClient<FeedbackForm>(env: env, path: "forms", additionalHeaders: [:])
}
func create(form: FeedbackForm) async throws -> FeedbackForm {
try await apiClient.create(token: token, item: form)
}
func read(key: String) async throws -> FeedbackForm {
try await apiClient.read(token: token, key: key)
}
func update(form: FeedbackForm) async throws -> FeedbackForm {
try await apiClient.update(token: token, item: form)
}
Data Model
Environment API PATH
JWT Token

12. APP API SERVICE
BREEZE LAMBDA API CLIENT
struct Environment {
static func dev() throws -> APIClientEnv {
try APIClientEnv(session: URLSession.shared, baseURL: "<API GATEWAY BASE URL FROM SERVERLESS DEPLOY>")
}
}
extension FeedbackForm: KeyedCodable {}
struct Logger: APIClientLogging {
func log(request: URLRequest) {
print(request)
}
func log(data: Data, for response: URLResponse) {
print(response)
let value = String(data: data, encoding: .utf8) ?? ""
print(value)
}
}

13. LAMBDA CODE
ONE LINE OF CODE !!!
import Foundation
import BreezeLambdaAPI
import BreezeDynamoDBService
import SharedModel
extension Form: BreezeCodable { }
BreezeLambdaAPI<Form>.main()
public protocol BreezeCodable: Codable {
var key: String { get set }
var createdAt: String? { get set }
var updatedAt: String? { get set }
}

14. SWIFT !!!
YES, I CAN UNDERSTAND IT!

15. INFRASTRUCTURE AS A CODE
SERVERLESS.YML
▸ API Gateway v2
▸ Lambda
▸ DynamoDB
▸ IAM
▸ Package

16. SERVERLESS.YML ?!?
LOOKS QUITE HARD !

17. HOW DO I START?

18. ▸ A SMALLER YML CONFIG
▸ COMMAND LINE TOOL GENERATES:
▸ PROJECT FOLDER
▸ SWIFT PACKAGE
▸ SERVERLESS.YML
▸ BUILD SCRIPT
▸ DEPLOYMENT SCRIPT
SERVERLESS WITH BREEZE
CODE GENERATION WITH BREEZE
service: swift-breeze-rest-form-api
awsRegion: us-east-1
swiftVersion: 5.7.3
swiftConfiguration: release
packageName: BreezeFormAPI
buildPath: build
cors: false
authorizer: #optional
name: appleJWT
type: JWTAuthorizer
issuerUrl: https://appleid.apple.com
audience:
- com.andrea.DemoApp #APP BUNDLE ID
breezeLambdaAPI:
targetName: FormAPI
itemCodable: Form
itemKey: formKey
httpAPIPath: /forms
dynamoDBTableNamePrefix: forms

19. CODE GENERATION
BREEZE COMMAND LINE
swift run breeze -c breeze.yml -t .build/temp

20. CODE GENERATION
BREEZE COMMAND LINE

21. CODE BUILD
BREEZE BUILD
./build.sh
❌
build
Docker image: swift:5.7-amazonlinux2

22. CODE BUILD
BREEZE BUILD
./build.sh

23. SERVERLESS DEPLOY
BREEZE DEPLOY
./deploy.sh
serverless.yml
build Deployment con
fi
guration
CloudFormation AWS Deployment
serverless deploy

24. SERVERLESS DEPLOY
BREEZE DEPLOY
./deploy.sh

25. SERVERLESS LIKE A BREEZE!

26. BREEZE WORKFLOW
STEP BY STEP WORKFLOW
▸ Git Clone https://github.com/swift-sprinter/Breeze
▸ Copy Breeze.yml con
fi
g from the README
▸ Add the Authorizer to the con
fi
g if you want to secure the API!!!
▸ Adjust the con
fi
guration
▸ Generate the code and customise the data model
▸ Build the Lambdas
▸ Deploy the Serverless
▸ Implement your app using the BreezeLambdaAPIClient

27. WHY SERVERLESS?
WHY SWIFT?
WHY BREEZE?

28. WHY SERVERLESS? WHY SWIFT? WHY BREEZE?
▸ Scalability
▸ Reduced Operational Overhead
▸ Pay per use
▸ Faster Time to market
▸ Easy Integration
WHY SERVERLESS?

29. WHY SERVERLESS? WHY SWIFT? WHY BREEZE?
▸ iOS Developers ❤ it!
▸ No need to learn a new language
▸ Modern and performant language
▸ Safe
▸ Expressive
▸ Fast
WHY SWIFT?

30. ▸ Quick Start!
▸ Project setup
▸ Build
▸ Deploy
▸ Full control
▸ Adaptable
▸ Open Source
WHY SERVERLESS? WHY SWIFT? WHY BREEZE?
WHY BREEZE?

31. GITHUB BREEZE
GITHUB.COM/SWIFT-SPRINTER/BREEZE

32. THANK YOU!

33. ANDREA SCUDERI - SENIOR IOS ENGINEER @ JUST EAT TAKEAWAY
STAY IN TOUCH!
▸ Twitter: @andreascuderi13
▸ Linkedin: https://www.linkedin.com/in/andreascuderi/
▸ Medium: https://medium.com/@andreascuderi73