Android Development with Kotlin, Part 3 - Code and App Management

St. Pölten University of Applied SciencesSt. Pölten University of Applied Sciences
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Android Development with Kotlin, Part 3
Code & App Management
Andreas Jakl
Digital Healthcare
FH St. Pölten
Platzhalter für möglichen
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Version 1.2

Andreas Jakl
▪ Focus areas
▪ AR / VR, mobile apps, sensors, interaction
technology, software architecture, open source
developer (NFC, Bluetooth Beacons)
▪ Microsoft MVP (Most Valuable Professional)
▪ mobility.builders community: Mobile Developer
After-Work Events
▪ Previous Experience
▪ Tieto, Start-up (Mopius), Nokia (Finland),
Siemens Mobile (Munich), FH Hagenberg
(Mobile Computing)
Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten
https://www.andreasjakl.com/
@andijakl
andreas.jakl@fhstp.ac.at
2

Contents
▪ Code Management
▪ Open Source
▪ Version Control & Git
▪ App Stores
▪ Testing Mobile Apps
▪ Automated Tests
▪ Visual Studio App Center
▪ Espresso Test Recorder
▪ Firebase Test Lab
▪ Robo Tests
▪ App Distribution
Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten 3

CODE MANAGEMENT
Licenses and Collaboration

Source Code Licenses
▪ Copyright
▪ Automatically applies to code you write
▪ You retain all rights
▪ https://choosealicense.com/no-license/
▪ Custom License
▪ Provide & sell software under your own terms
▪ Example: Windows 10: https://www.microsoft.com/en-
us/Useterms/Retail/Windows/10/UseTerms_Retail_Windows_10_English.htm
▪ But: difficult for other companies to use
▪ Would need to do a legal check of your license
▪ What happens if your company is closed?
©

Software Patents
▪ Europe
▪ Source code by itself not patentable (only copyright)
▪ But: broader “computer implemented inventions” that
solves a technical problem in a
“novel or non-obvious manner”
▪ US
▪ Generally patentable
▪ But do not necessarily “win” if challenged in court and not concrete enough
Source: https://fsfe.org/campaigns/swpat/swpat.en.html
https://en.wikipedia.org/wiki/Software_patents_under_the_European_Patent_Convention
https://www.epo.org/news-issues/issues/software.html
https://en.wikipedia.org/wiki/Software_patents_under_United_States_patent_law

Open Source
▪ Software must be:
▪ Freely used
▪ Modified
▪ Shared
▪ Licenses
▪ Approved licenses by OSI: https://opensource.org/licenses
▪ Choose a license: https://choosealicense.com/
▪ Most popular: GPL, Apache, MIT
Image source: Open Source Initiative by Simon Phipps, CC BY 2.5
https://en.wikipedia.org/wiki/File:Opensource.svg

Version Control & Collaboration
▪ Advantages
▪ Teams & Collaboration
▪ Tracking changes & history
▪ Branches for stable release +
development
▪ Most popular:
▪ Git
Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten 8Source: https://www.openhub.net/repositories/compare

Git Basics
▪ Store finished changes with “commit”s
▪ Default “Master” branch for main version
▪ “HEAD” = current version
commit commit commit
HEAD of master branch

Git Basics
working
directory
index
(stage)
HEAD
add commit
Some Git clients simplify and do this in one step

Git Basics
working
directory
index
(stage)
HEAD
add commit
your PC server
HEAD
push
pull

Using GIT
▪ GIT Tools
▪ Windows, Mac, Linux
▪ Optional: more powerful user interfaces
▪ TortoiseGit – great Windows Explorer integration: https://tortoisegit.org/
▪ GitHub Desktop – https://desktop.github.com/

Hosting GIT Repositories
▪ Online services for collaboration
▪ GitHub: free for open source projects
▪ GitLab: install GIT on own server (free)
▪ Visual Studio Team Services
▪ Free for 5 users + MSDN subscribers, also for closed source projects
▪ Includes agile project planning, DevOps (automated testing &
deployment)
▪ https://www.visualstudio.com/team-services/

Create / Clone Git Repository

Git versioning:
History, contributors & changes
(GitHub Desktop app)

Git versioning:
Reviewing your code changes before committing
(GitHub Desktop app)

APPS & USER EXPERIENCE
How to bring the technology to your customers?

App Stores Are Merciless

Source: App Annie, Record Levels of App Downloads & App Store Consumer Spend in Q4 2017
https://www.appannie.com/en/insights/market-data/app-downloads-consumer-spend-q4-2017/

„Within 3 days, an app
loses 77% of its users“
@andrewchen New data shows losing 80% of mobile users is normal, and why the best apps do better
http://andrewchen.co/new-data-shows-why-losing-80-of-your-mobile-users-is-normal-and-that-the-best-apps-do-much-better/Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten 21

Source: Android, & Apple, & Google, & Microsoft, & AppBrain, & BlackBerry, & Various sources
(WindowsCentral.com, & International Games Week Berlin), & Amazon, & VentureBeat, &
CNET. (n.d.). Number of apps available in leading app stores as of March 2017. In Statista - The
Statistics Portal. Retrieved January 27, 2018, from
https://www.statista.com/statistics/276623/number-of-apps-available-in-leading-app-stores/.

Flurry: Enter the Matrix: App Retention and Engagement
http://flurrymobile.tumblr.com/post/144245637325/appmatrixAndroid Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten 23

Your Fate lies in the

App Reviews
Bin Lu, et al.: Why People Hate Your App – Making Sense of User Feedback in a Mobile App Store. Carnegie Mellon University, 2013. Data from 13 million user reviews, 171,439 apps
Claudia Iacob, Rachel Harrison: “Retrieving and Analysing Mobile Apps Feature Requests from Online Reviews”, Oxford Brookes University, 2013
Kahlid. H, et al.: “What Do Mobile App Users Complain About? A Study on Free iOS Apps”, Queen’s University, Kingston, 2014
Gunwoong Leea, T. S. Raghua: “Determinants of Mobile Apps' Success: Evidence from the App Store Market”, 2014
0
2 000 000
4 000 000
6 000 000
8 000 000
Downloads
Negative reviews
Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten25

Reviews vs Downloads
Review count & rating correlate to downloads
Bin Lu, et al.: Why People Hate Your App – Making Sense of User Feedback in a Mobile App Store.
Carnegie Mellon University, 2013
Data from 13 million user reviews, 171,439 apps
Average rating: 3.9
(standard deviation: 1.48)
0
2 000 000
4 000 000
6 000 000
8 000 000

Review Analysis
▪ Analysis
▪ Most frequent complaints
▪ Functional errors
▪ Feature requests
▪ App crashes

Review Analysis
▪ Analysis
▪ Most negative impact
▪ Privacy and ethical issues
▪ Hidden app costs

TESTING STRATEGIES

Thousands of Mobile Devices in Use
http://opensignal.com/reports/2015/08/android-fragmentation/
http://stats.unity3d.com/mobile/device-ios.html
OpenSignal: 24,000 distinct Android
devices used their app in 2015

Capturing Crash Data

Monitoring Reviews
Bin Lu, et al.: Why People Hate Your App – Making Sense of User Feedback in a Mobile App Store.
Carnegie Mellon University, 2013

Static Code Analysis

Emulator / Simulator
Emulator
Emulates real
hardware
+ more accurate
– slow
Android
Simulator
Simulates device
behavior
+ faster
– less accurate
iOS / Windows

Reliable?
0%of your users will run your app on an emulator

Automated UI Tests
How many tests can you run per hour / build / release?

Automated UI Tests
Number of builds
Cost
Automated tests
Manual tests

Own Devices
How many test devices do you have?

Visual Studio App Center
▪ Automated tests
▪ UI interaction
▪ Device features (GPS, etc)
▪ Performance
▪ 3,300+ devices
▪ Android & iOS
▪ http://appcenter.ms/signup

Workflow

+ Continuous Integration

Executing Tests

Android App Testing
▪ Local JUnit test (test)
▪ Minimize execution time
▪ No Android framework dependencies
▪ Instrumented test, runs on device (androidTest)
▪ Lets you control your running app
▪ Automate user interaction (UI tests)
▪ Overview: https://developer.android.com/studio/test/index.html

Exercise: Espresso Test Recorder
▪ Open HelloWorld or GreetingApp solution project
▪ Record UI interactions
▪ Run > Record Espresso Test
▪ Execute tests:
▪ Right-click MainActivityTest > Run
▪ Further steps
▪ Change app so that it fails the test
▪ Add EditText to app, test entering text
▪ Update TextView with user-entered text
▪ Manually extend test script to check if user-entered text appears
▪ https://developer.android.com/studio/test/espresso-test-recorder.html

Firebase Test Lab
▪ Real devices in Google data center
▪ https://firebase.google.com/docs/test-lab/
▪ Robo test
▪ Explores UI structure
▪ Automatically simulates user activities
▪ Optional: robo scripts for more control
▪ Scripted tests
▪ Using Espresso
▪ Reports
▪ Video, screenshots, device logs, performance, crash logs
Image credits: Google,
https://firebase.google.com/docs/test-lab/

Exercise: Run Tests in the Cloud
▪ Tools > Firebase > Test Lab >
Run Firebase Test Lab for Android
▪ Connect your app to Firebase
▪ Billing plan
▪ Spark = free: daily quota,
10 virtual tests / day,
5 physical tests / day
▪ Run test configuration

Exercise: Firebase Console
▪ Check test report: Firebase console

Exercise: Robo Test
▪ Run Robo test from Firebase Console
▪ Upload APK:
▪ <project>appbuildoutputsapkdebug

Developing & Maintaining Apps
is a Challenge!

App Purge
Apple:
- Purged 47,300 apps in October 2016
(14,000 apps / month purged on average)
- 2017: 180,000+ apps not compatible with iOS 11
(64 bit now required)
Sensor Tower: Worldwide iOS App Store App Removals Increased 238% in October
https://sensortower.com/blog/app-store-purge
Nearly 200,000 Current Apps Could Be Incompatible with iOS 11
https://sensortower.com/blog/ios-11-incompatible-apps
Dr. Windows: Bereinigung des Windows Store noch nicht abgeschlossen - nur noch ein Drittel aller Apps übrig
http://www.drwindows.de/content/11332-bereinigung-windows-store-noch-abgeschlossen-nur-noch.html
Google Android Developers Blog: How we fought bad apps and malicious developers in 2017
https://android-developers.googleblog.com/2018/01/how-we-fought-bad-apps-and-malicious.html
Microsoft:
- 2/3 of all apps purged between Oct – Nov 2016
(330k -> 125k)
… but we still have 3 million apps only for the iPhone.
Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten
Google:
- 2017: took down 700,000 apps that violated Google Play policies
50

How to Survive.

There is Hope!
Tune: No, Americans do not install an average of zero apps per month
https://www.tune.com/blog/no-the-average-american-does-not-download-0-apps-each-month/
The true number ist most likely even higher: 2 – 3 app installs / month

APP DISTRIBUTION
Payments, Fees and Certificates

App Store Overview
Android Development with Kotlin, Part 3 | 2018 | Andreas Jakl | FH St. Pölten 54Source: https://en.wikipedia.org/wiki/List_of_mobile_app_distribution_platforms
Apps 2,800,000 2,200,000 669,000 600,000
Fee $25 (1x) $99 / year $0 (1x, student)
$19 (1x, individual)
$99 (1x, company)
$0
Cut per sale
(from net)
70% 56 – 71% (depends
on country)
70%
(85% for app
subscriptions)
70%

Google Play Store
▪ Prerequisites:
▪ Google Account
▪ Credit card ($25 fee)
▪ Sign-Up:
▪ Developer name
▪ Email Address
▪ Website
▪ Phone Number
▪ Instant activation
▪ Optional further steps
▪ Invite Co-Workers
▪ Set up merchant account for paid apps

Quality Guidelines
▪ Checklist
▪ Quality criteria & associated tests
▪ Work through tests, especially for 1st app
▪ https://developer.android.com/develop/quality-
guidelines/index.html

App Signing
▪ All APKs digitally signed
▪ Android Studio: Debug certificate
▪ Automatically generated:
C:Users<name>.androiddebug.keystore
▪ Not trusted for publishing to the Play Store
▪ Certificate valid for 365 days
▪ https://developer.android.com/studio/publish/app-signing.html

App Publishing
▪ App signing key
▪ Needed for updates!
▪ Google Play App Signing OR manual app signing
▪ https://support.google.com/googleplay/android-developer/answer/7384423

THANK YOU!

Android Development with Kotlin, Part 3 - Code and App Management

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