lesson3.2_repeatElement

Lesson 3.2: repeatElement

Problem statement

Write an app which spits out an infinite series of "hello" messages to the debugging console, using func repeatElement.

Problem project

You can use the project in the problem folder of this repo as a starting point.

Note: I have omitted the Carthage folder from the problem project, because it includes large binary files. In order to use the this project, you will need to run carthage update --platform iOS.

Solution

ViewController.swift:

import UIKit
import RxSwift
import RxCocoa

class InfiniteHelloGenerator
{
    class func generate() -> Observable<String>
    {
        return RxSwift.repeatElement("hello", MainScheduler.sharedInstance)
    }
}

class ViewController: UIViewController {

    let disposeBag = DisposeBag()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        InfiniteHelloGenerator.generate().subscribeNext { (s) -> Void in
            debugPrint(s)
        }.addDisposableTo(disposeBag)
    }
}

Discussion:

RxSwift includes a number of convenience variations on func generate, and the rest of this chapter will be about exploring those.

Here, we use func repeatElement, which truly makes the implementation of InfiniteHelloGenerator trivial:

Start up the app and verify that you see an infinite stream of "hello" in the console:

"hello"
"hello"
"hello"
...

New concepts to explore

• Open up RxExample.xcodeproj.
  • Take a look at func repeatElement in Observable+Creation.swift

Solution project

My solution is included in the solution folder of this repo.

Note: I have omitted the Carthage folder from the solution project, because it includes large binary files. In order to run the this project, you will need to run carthage update --platform iOS.