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Android Development

JsonBroadcaster | Android-Arsenal.com

Written by News One


Update the UI state of your Android and iOS apps at runtime.

Motivation

Updating the UI State at runtime is a very useful tool for rapid prototyping and validation purposes. It also adds the benefit that it can be used by the whole testing team, be it developers, designers, quality assurance, etc.

demo.mov

How does it work

Android

Android Debug Bridge (ABD) is used to send a broadcast signal to the desired application with a json payload as an extra.

adb shell am broadcast -p [package] -a [action] -e [extra key] [extra value]

On the application side there’s a BroadcastReceiver listening for theses payloads. Upon successful deserialization, a fresh state will be emitted, consequently triggering a UI update.

Availability: all simulators and/or physical devices (even with wifi debug) connected.

iOS

Apple’s Xcode developer tools provides a command-line tool for interacting with the iOS Simulator.
This tool allows you to simulate the process of sending push notifications to a device:

xcrun simctl push [UDID] [bundle id] [path to .apns]

On the application side there’s a NotificationBroadcaster actively monitoring incoming notifications. These notifications are then relayed to internal observers within the application. Upon successful deserialization, a fresh state will be emitted, consequently triggering a UI update.

Availability: all booted simulators.

Installation

Android

Add the library dependency:

implementation("com.github.guilhe:json-broadcast-handler:${LATEST_VERSION}'")

Swift Package Manager

The Swift implementations are available via the Swift Package Manager.

  1. In Xcode go to File > Add Packages... and provide the URL https://github.com/GuilhE/JsonBroadcaster.git;
  2. Use the commit hash from the latest tag JsonBroadcasterHandler-x.

CocoaPods

If you use CocoaPods add the following to your Podfile:

pod 'JsonBroadcasterHandler', :git => 'https://github.com/GuilhE/JsonBroadcaster.git', :tag => 'JsonBroadcasterHandler-x'

Usage: developers

Android

  1. Your UiState classes must be annotated with kotlinx.serialization.Serializable (dependency):

    @Serializable
data class UiState(val memberA: String, val memberB: String)

  2. Create a BroadcastUiModelHost implementation to listen for state updates, as shown bellow:

    private val host = object : BroadcastUiModelHost<UiState>(coroutineScope, UiState.serializer()) {
    override fun updateState(new: UiState) {
        //...
    }
}

  3. Add it where it fits best in your project, examples:

    If you are using androidx.lifecycle.ViewModel you can do the following:

    class MatchViewModel : ViewModel() {

    private val _uiState = MutableStateFlow(MatchUiState(home = Team("PRT", "????????"), away = Team("BRA", "????????")))
    val uiState: StateFlow<MatchUiState> = _uiState

    private val host = object : BroadcastUiModelHost<MatchUiState>(viewModelScope, MatchUiState.serializer()) {
        override fun updateState(new: MatchUiState) {
            _uiState.update { new }
        }
    }
}

    But actually you don’t need a ViewModel, you can simply use a @Composable for instance:

    @Composable
fun MatchScreen() {
    var uiState: MatchUiState by remember { mutableStateOf(MatchUiState(home = Team("PRT", "????????"), away = Team("BRA", "????????"))) }
    LaunchedEffect(Unit) {
        val host = object : BroadcastUiModelHost<MatchUiState>(this, MatchUiState.serializer()) {
            override fun updateState(new: MatchUiState) {
                uiState = new
            }
        }
    }
    Match(uiState)
}

    And the beauty of it is that you may choose whatever suits you best: ViewModel, @Composable, Activity, Fragment, etc…

  4. To disable it, for instance in release builds, override the receiver declaration in the AndroidManifest by adding a manifestPlaceholders property in the build.gradle:

    android {
    buildTypes {
        getByName("release") {
            manifestPlaceholders["enableJsonBroadcastReceiver"] = false
        }

        getByName("debug") {
            manifestPlaceholders["enableJsonBroadcastReceiver"] = true
        }
    }
}
    <receiver
    android:name="com.broadcast.handler.JsonBroadcasterReceiver"
    android:exported="${enableJsonBroadcastReceiver}"
    tools:replace="android:exported">
    <intent-filter>
        <action android:name="JsonBroadcaster.extra" />
    </intent-filter>
</receiver>

iOS

  1. Your UiState classes must implement the Codable protocol:

    struct UiState: Codable {
    let memberA: String
    let memberB: String
}

  2. Create a BroadcastUIModelHost instance inside a class to listen for state updates, as shown bellow:

    private var uiModelHost: BroadcastUIModelHost<UiState>!
init() {
     uiModelHost = BroadcastUIModelHost(initState) { [weak self] newState in
         //...
     }        
 }

  3. Add it where it fits best in your project, example:

    If you are using an ObservableObject you can do the following:

    import SwiftUI
import JsonBroadcasterHandler

class MatchViewModel: ObservableObject {
   private var uiModelHost: BroadcastUIModelHost<MatchUiState>!
   @Published var state: MatchUiState = MatchUiState(home: Team(country:"PRT", flag:"????????"), away: Team(country:"BRA", flag:"????????"))
 
   init() {
     uiModelHost = BroadcastUIModelHost(state) { [weak self] newState in
         self?.state = newState
     }
   }
}

    And the beauty of it is that you may choose whatever suits you best, SwiftUI or UIKit:

    struct MatchScreen: View {
   @StateObject private var viewModel = MatchViewModel() 

   var body: some View {
     ZStack { }
     .onReceive(viewModel.$state) { new in
         //...
     }
 }

    class MatchScreen: UIViewController {
   private var viewModel: MatchViewModel!
   private var cancellables = Set<AnyCancellable>()

   override func viewDidLoad() {
     super.viewDidLoad()
     viewModel = MatchViewModel()
     viewModel.$state
         .receive(on: DispatchQueue.main)
         .sink { [weak self] state in
             self?.updateUI(with: state)
         }
         .store(in: &cancellables)
   }
   
   private func updateUI(with state: MatchUiState) {
     //...
   }
}

  4. Inside your AppDelegate register for RemoteNotifications and forward them with the NotificationBroadcaster:

    import UIKit
import JsonBroadcasterHandler

class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        UNUserNotificationCenter.current().delegate = self
        application.registerForRemoteNotifications()
        return true
    }
    
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        NotificationBroadcaster.broadcast(notification)
    }
}

    tip: You may create a compiler custom flags, DEBUG_MODE, to encapsulate the NotificationBroadcaster:

    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
   #if DEBUG_MODE
      NotificationBroadcaster.broadcast(notification)
   #endif
}

Usage: testing team

Android

  1. Google’s Android SDK must be installed in order to use command line tools;
  2. Ask for an installed version of the app (wifi debug or cable connected);
  3. Use the desktopApp GUI.

iOS

  1. Apple’s XCode must be installed in order to use command line tools;
  2. Open XCode and run a simulator with the app;
  3. Use the desktopApp GUI.

Desktop app

Although we can use the terminal to send commands, it’s not practical. The desktopApp provides a simple user interface to help us with that task.

To run it you can either:

  • Clone this project and type ./gradlew :desktopApp:run in the terminal.
  • Download a .dmg (only MacOS) and install it. Get it here.

note: due to security reasons, since this app is not from an Identified Developer, MacOS will block its execution. To by pass it you’ll need to click in “Open Anyway” in System Settings under Security. It’s only needed once:

(This wont happen with the first approach)

Playgrounds

Use the following payload to get you started:

{
   "home":{
      "country":"PRT",
      "flag":"????????"
   },
   "away":{
      "country":"BRA",
      "flag":"????????"
   },
   "homeGoals":0,
   "awayGoals":0,
   "started": false,
   "running": false,
   "finished": false
}

Android

Inside the sample module you’ll find a playground app ready for you to test it.

To run it you can either:

  • Clone this project and type ./gradlew :androidApp:installDebug in the terminal.
  • Download the sample .apk and install it. Get it here.

The applicationId is com.jsonbroadcaster.matchday

iOS

Inside the sample-ios folder you’ll find a playground app ready for you to test it.

To run it:

  • Open it in Xcode and run standard configuration.
  • Import JsonBroadcaster using your method of choice.

LICENSE

Copyright (c) 2022-present GuilhE

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.



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