lesson2.1_backgroundcolor

Lesson 2.1: RxSwiftButtonBackgroundColorDemo

Problem statement

Make an app which:

• Has a button
• Changes the view's background color to green when the button is pressed.

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!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        button.rx_tap.subscribeNext { [weak self] () -> Void in
            self?.view.backgroundColor = UIColor.greenColor()
        }
        
    }
}

Discussion:

We subscribe to button's rx_tap property. rx_tap is an Observable which emits an Event whenever the button gets tapped.

rx_tap's responsibility is to convert the TouchUpInside target/action into an RxSwift Event.

By subscribing, we tell rx_tap to run a closure anytime it emits an Event. In that closure, we set view.backgroundColor to greenColor.

New concepts to explore

• Open up RxExample.xcodeproj.
  • Take a look at Observable.swift
  • Take a look at ObservableType.swift
  • Take a look at Event.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.