iOS Dev @ inloop. Always on the lookout for the next best thing in software abstraction, methodology and programming paradigms.

1. FRPs ReactiveCocoa

2. FUNCTIONAL
• stateless; state is derived instead
(cell c = cell a + cell b)
• immmmmmmmutable data
• dôraz na high-order funkcie (ktoré produkujú vyýstup na
základe vstupov)
• funkcie ako 1st class objekty

3. Immutable
Stateless
(Gotcha *) ignorujúc minulosť

4. REACTIVE
• práca s asynchrónnymi data streams
• …taktiež s nested callbacks, complexnými list filtering/
transformáciami alebo timing concerns
• integruje koncept času a kompozíciu udalostí spolu s
funkcionálnym programovaním.
• od MS, spolu aj s MVVM

5. ReactiveCocoa
• obj-c / swift implementácia pre iOS & Mac OS X
• zjednocuje programovacie API pre všetky eventy
• KVO, delegate, notifications, block syntax, target-action
• od 3.0 podpora Swift

6. BUILDING BLOCKS
RACSequence RACSignal
Stream
• push-driven stream• pull-driven stream
• oba zdieľajú viacero spoločných operátorov

7. RACSequence
• lazily-loaded kolekcie
• podobný účel ako NSArray
• pridáva funkcie, ktoré Foundatin nemá: map*, filter, fold/reduce…
• objekty kolekcie netransformujú, až kým nie sú vytiahnuté (for-in, etc.)
RACSequence *normalizedLongWords = [[words.rac_sequence
filter:^ BOOL (NSString *word) {
return [word length] >= 10;
}]
map:^(NSString *word) {
return [word lowercaseString];
}];
* swift už map vie

8. RACSignal
• rúra, ktora nesie hodnotu ( input > transform > output )
• signály môžu byť (a budú) reťazené (funkcia pojme
funkciu)
• Chaining of Dependent Operations
• Parallelizing Independent Work
• (Hint *) Signály sú interne postavené na KVO

9. RACSignal (cont.)
• signál posiela 3 druhy eventov: next, finished, error
• next nesie naše dáta ( = čokoľvek)
• Subscribe (na základe čoho robíme side-effects)
• binding pomocou RAC()
• nahradzujú @property (niekedy)
• neprepisuje/nemodifikuje pôvodný stream. (immutability)
• 0, 1, alebo > 1 subscriberov
• alebo si ich vytvoríme: RACObserve() (zabalí
dynamickú property)

10. RACSignal
*formValid
=
[RACSignal
combineLatest:@[
self.username.rac_textSignal,
self.emailField.rac_textSignal,
self.passwordField.rac_textSignal,
self.passwordVerificationField.rac_textSignal
]
reduce:^(NSString
*username,
NSString
*email,
NSString
*password,
NSString
*passwordVerification)
{
return
@([username
length]
>
0
&&
[email
length]
>
0
&&
[password
length]
>
8
&&
[password
isEqual:passwordVerification]);
}];
RAC(self.createButton.enabled)
=
formValid;
emailField
userNameField
passwordVerifi
cationField
passwordField
combineLatest reduce formValid
NSNumber
(boolean)
NSString
NSString
NSString
NSString
4x NSString

11. -­‐
(RACCommand*)rac_searchCommand
{
if
(!_searchCommand)
{
@weakify(self)
_searchCommand
=
[[RACCommand
alloc]
initWithSignalBlock:^RACSignal
*(NSDictionary
*parameters)
{
@strongify(self)
return
[[self.searchHelper
rac_searchWithScheduler:[RACScheduler
scheduler]
parameters]
catch:^RACSignal
*(NSError
*error)
{
DLog(@"Remote
Search
Error");
return
[RACSignal
return:RACTuplePack(@[])];
}];
}];
}
return
_searchCommand;
}
-­‐
(void)viewModelSetup
{
[[[self.rac_searchCommand
executionSignals]
flatten]
subscribeNext:^(NSArray
*
array)
{
[self.data
=
array];
}];
}
ViewModel

12. func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath:
NSIndexPath) -> UITableViewCell {
...
cell.model = searchVM!.modelForResultAtIndexPath(indexPath)
...
return cell
}
override
func
viewDidLoad()
{
RACObserve(self.searchVM,
"data").ignore(nil).subscribeNext
{
[unowned
self]
(any)
-­‐>
Void
in
self.searchResultsTable.reloadData()
}
}
func searchBarSearchButtonClicked(searchBar: UISearchBar) {
println("search (searchBar.text)")
self.searchVM?.rac_searchCommand.execute(["query" : searchBar.text])
}
ViewController
searchButton.enabled <~ viewModel.rac_searchCommand.executing

13. -­‐
(void)awakeFromNib
{
RAC(self.titleLabel,
text)
=
[RACObserve(self,
model.title)
ignore:nil];
RACSignal
*
colorSignal
=
[[RACObserve(self,sectionModel.sectionColorRGBString)
ignore:nil]
map:^id(NSString*
value)
{
return
[UIColor
colorFromString:value];
}];
RAC(self.resultImage,
backgroundColor)
=
colorSignal;
}
TableViewCell

14. SWIFT
let usernameTextField: UITextField =
UITextField()
usernameTextField.rac_textSignal()
.mapAs {
(text: NSString) -> NSNumber in
return text.length
}.filterAs {
(number: NSNumber) -> Bool in
return number > 3
}.subscribeNextAs {
(length: NSNumber) in
println(length)
}
OBJ-C
UITextField *usernameTextField =
[[UITextField alloc] init];
[[[usernameTextField.rac_textSignal
map:^(NSString *value) {
return @(value.length);
}]
filter:^BOOL(NSNumber *value) {
return value > 0;
}]
subscribeNext:^(NSNumber *length) {
NSLog(@"%d", [length intValue]);
}];

15. Fluent API
[[[[[[[[[[[[[[[[I dont] think] fluent] interface] patterns] will] be]
useful] unless] you] want] to] write] methods] like] this];

16. zip()
map() defer()
catch() reduce()
dinstinctUntilChanged()
deliverOn()
filter()
throttle()
flatten()
merge()
https://github.com/dogwith1eye/
101RACSamples
…
…

17. ?
MOTIVATION

18. https://github.com/dogwith1eye/101RACSamples
github.com/ColinEberhardt/
github.com/artsy/eidolon
INSPIRATION