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Questions tagged [reactive-cocoa]

ReactiveCocoa (RAC) is a Swift framework inspired by Functional Reactive Programming. It provides APIs for composing and transforming streams of values.

ReactiveCocoa (RAC) is a Swift framework inspired by Functional Reactive Programming. It provides APIs for composing and transforming streams of values.

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Chaining dependent signals in ReactiveCocoa

In ReactiveCocoa, if we chaining several dependent signals, we must use subscribeNext: for the next signal in the chain to receive the value previous signal produced (for example, a result of an asynchronous operation). So after a while, the code…
Sergey Mikhanov
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A ViewModel pattern for iOS apps with ReactiveCocoa

I'm working on integrating RAC into my project with the goal of creating a ViewModel layer that will allow easy caching/prefetching from the network (plus all of the other benefits of MVVM). I'm not especially familiar with MVVM or FRP yet, and I'm…
Evan Cordell
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What are the reference ownership semantics of ReactiveCocoa?

When I create a signal and bring it into the scope of a function, its effective retain count is 0 per Cocoa conventions: RACSignal *signal = [self createSignal]; When I subscribe to the signal, it retains the subscriber and returns a disposable…
bvanderveen
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Why Does RACCommand's block return a signal?

I've been learning a lot about ReactiveCocoa but one thing still puzzles me: why does the signal block on RACCommand return a signal itself? I understand the use cases of RACCommand, its canExecute signal and signal block, and how it can be hooked…
Ash Furrow
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How to using ReactiveCocoa to transparently authenticate before making API calls?

I am using ReactiveCocoa in an app which makes calls to remote web APIs. But before any thing can be retrieved from a given API host, the app must provide the user's credentials and retrieve an API token, which is then used to sign subsequent…
bvanderveen
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Difference between RACAble(), RACObserve() and RACBind() in Reactive Cocoa

I'm new to Reactive Programming. I have gone through the documentation of Reactive Cocoa but couldn't realize the differences between RACAble(), RACObserve() and RACBind(). Please, help ,me in understanding the aspects by some example code…
TryinHard
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Has anybody made self updating mutable table view based on a RACSignal?

Now that there's a full support for KVO, has anybody made a mutable table view that takes a RACSignal as its dataSource? Ideally something that doesn't require any configuration. RACSignal *commentsSignal; UITableView *table = [UITableView…
Michael
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Explanation of how weakify and strongify work in ReactiveCocoa / libextobjc

I understand that you should use @weakify @strongify to avoid retain cycles but I don't completely understand how they actually achieve this?
nacross
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Objective-C self->_ivar access with explicit vs implicit self->

General Problem Until now, I always thought self->_ivar is equivalent to _ivar. Today I found out that this is not entirely true. See, for example the following code snippet: @interface TestClass : NSObject { NSString…
Johannes Weiss
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Difference between catch: and subscribeError:

In ReactiveCocoa, what's the difference between the subscribeError: method vs. catch:? Why would you want to return a signal in catch:?
Ash Furrow
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How to use Reactive Cocoa with notifications

How can I create a signal out of a notification name? For example, I want to go from: [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(userDidChange:) …
meisel
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ReactiveCocoa example with NSMutableArray push/pop?

Could someone provide a one-line example of using ReactiveCocoa abstractions to achieve something like this: // pseudo-code NSMutableArray *array = @[[] mutableCopy]; RACSignal *newValue = RACAbleWithStart(array); // get whole array or maybe just…
Nik
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How do I create a ReactiveCocoa subscriber that receives a signal only once, then unsubscribes/releases itself?

I'm currently registering a subscriber to a property signal like this: [RACAble(self.test) subscribeNext:^(id x) { NSLog(@"signal fired!"); }]; The default functionality is that it fires every single time self.test is changed, but I just…
zakdances
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MVVM and pushing a ViewController: where to initialize the next ViewController and ViewModel, and push on the new view?

I'm thinking through the structure of a very simple ViewModel and ViewController for a test application. I have something akin to: FirstViewController.m: - (IBAction)launchButtonSelected:(id)sender { [self.viewModel…
cbowns
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Meaning of Objective-C macros prefixed with an at (@) symbol

The ReactiveCocoa framework makes use of weakify and strongify macros, both of which are preceded by an '@' symbol. Here's an example (From this file). - (RACSignal *)rac_textSignal { @weakify(self); return [[[[RACSignal …
ColinE
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