Little intro to the reactive programming paradigm

2. MY AFFAIR
REACTIVECOCOA
with
FUNCTIONAL
REACTIVE
PROGRAMMING

4. FUNCTIONAL
REACTIVE
PROGRAMMING

5. // Imperative programming
var x = 1, y = 2, z = y + x;
console.log(z); //3
x = 2;
console.log(z); //3
// Reactive programming
var x = 1, y = 2, z = y + x;
console.log(z); //3
x = 2;
console.log(z); //4

6. FUNCTIONAL
PROGRAMMING
REACTIVE

9. FUNCTIONAL PROGRAMMING
DECLARATIVE EVALUATION OF PURE
FUNCTIONS TO CREATE IMMUTABLE
PROGRAMS AND SO AVOID SIDE
EFFECTS THAT ARE EXTERNALLY
OBSERVED.

10. PURE FUNCTIONS
DECLARATIVE PROGRAMMING
REFERENTIAL TRANSPARENCY
INMUTABILITY
// Imperative programming
var arrayFoo = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
for (var i = 0; i < arrayFoo.length; i++) {
arrayFoo[i] = Math.pow(arrayFoo[i], 2);
}
array; // [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
// Declarative programming
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9].map(num => Math.pow(num, 2));
// [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

11. PURE FUNCTIONS
DECLARATIVE PROGRAMMING
REFERENTIAL TRANSPARENCY
INMUTABILITY
// Impure function
var likes = 0;
function addLike() {
return ++likes;
}
// Pure function
function addLike(likes) {
return ++likes;
}
addLike(addLike(0)); // 2

12. DECLARATIVE PROGRAMMING
REFERENTIAL TRANSPARENCY
INMUTABILITY
PURE FUNCTIONS
// Referential transparent function
int plusOne(int x)
{
return x+1;
}
// Referential opaqueness function
int G = 10;
int plusG(int x)
{//G can be modified externally returning different values.
return x + G;
}

13. DECLARATIVE PROGRAMMING
REFERENTIAL TRANSPARENCY
INMUTABILITY
PURE FUNCTIONS
// Referential transparent function
int plusOne(int x)
{
return x+1;
}
// Referential opaqueness function
int G = 10;
int plusG(int x)
{//G can be modified externally returning different values.
return x + G;
}

14. REACTIVE
PROGRAMMING
FUNCTIONAL

15. : https://goo.gl/NaMmJ
: https://goo.gl/sGSwMS
Reactive programming is
programming with asynchronous data streams.

16. A stream is a sequence of ongoing events ordered in time.

17. HANDS ON!

20. // RxSwift LoginViewModel
struct LoginViewModel {
let usernameBGColor: Driver<UIColor>
let passwordBGColor: Driver<UIColor>
let credentialsValid: Driver<Bool>
init(usernameText: Driver<String>, passwordText: Driver<String>) {
let usernameValid = usernameText
.distinctUntilChanged()
.throttle(0.3)
.map { $0.utf8.count > 3 }
let passwordValid = passwordText
.distinctUntilChanged()
.throttle(0.3)
.map { $0.utf8.count > 3 }
usernameBGColor = usernameValid
.map { $0 ? BG_COLOR : UIColor.white }
passwordBGColor = passwordValid
.map { $0 ? BG_COLOR : UIColor.white }
credentialsValid = Driver.combineLatest(usernameValid, passwordValid) { $0 && $1 }
}
func login(_ username: String, password: String) -> Observable<AutenticationStatus> {
return AuthManager.sharedManager.login(username, password: password)
}