README.md

Lesson 2.2: DisposeBag

Problem statement

Add proper memory management to RxSwiftButtonBackgroundColorDemo from Lesson 2.1.

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 ViewController: UIViewController {

    @IBOutlet weak var button: UIButton!
    
    var disposeBag = DisposeBag()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        button.rx_tap.subscribeNext { [weak self] () -> Void in
            self?.view.backgroundColor = UIColor.greenColor()
        }.addDisposableTo(disposeBag)
        
    }
}

Discussion:

There is a bit of boilerplate which we must accept with RxSwift, and that is using a DisposeBag to properly handle memory management of the Observables.

Basically, anytime you subscribe to an Observable, the result of that subscription needs to be added to a DisposeBag.

FIXME: is [weak self] actually needed in the context of RxSwift?

New concepts to explore

• Open up RxExample.xcodeproj.
  • Take a look at DisposeBag.swift
  • Take another look at ObservableType.swift. Note that func subscribe returns a Disposable.

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.