Mobile App OS: Platforms and Benefits

• Mobile App 1 Reviewer - 3rd Quarterly Exam

Mobile Operating System

• Exclusively built for mobile devices like smartphones, tablets, PDAs
• Responsible for defining features and functions including keypads, application synchronization, and text messaging

Current Software Platforms

• Android, by Google, is a commonly installed mobile OS with support from manufacturers and open-source access
• iOS (originally iPhone OS), by Apple, is exclusively for Apple hardware with multi-touch gestures
• Windows Phone, by Microsoft, features real-time updating apps and full support for Microsoft products
• Other Mobile OSes include Blackberry (exclusive to Blackberry phones) and Symbian (discontinued OS last used by Nokia)

Benefits of Mobile Applications

• Convenience: Users can access and share information anytime, anywhere, often without internet
• Interactivity: Touch-based user input allowing greater control
• Personalization: User customizable settings
• Speed: Eliminates loading wait due to stored information
• Productivity: Facilitates report writing, reading, presentation, multimedia management, and sharing

Development Environments

• Integrated Development Environments (IDEs) are packaged as application programs

Official IDEs for Mobile OSes

• Android Studio: Official IDE for Android development based on IntelliJ IDEA, includes code templates, a rich layout editor, and Google Cloud Platform support
• Xcode: Create apps for iPhone and iPad, allowing users to build and run apps on Apple devices; features user interface testing
• Swift: The programming language used by Apple for iOS, OS X, and watchOS development
• Visual Studio: Flexible IDE for creating apps for Windows, Android, and iOS, with features like Universal Windows Platform development and multiple language support, UWP apps run on any Windows-powered device

Factors to Consider in Mobile App Development

• Platforms and Device Compatibility: Consider the target platform, technology, and required mobile capabilities
• Screen Size: Simplify the design and rethink navigation for smaller screens
• Screen Density: Avoid hard-coded pixel values to prevent UI scaling issues on higher-end phones
• Phone Function Integration: Integrate phone-specific functions, like calls
• Resource Management: Optimize code due to limited computing power

Android App Development Basics: Fundamentals

• Android Apps: Programs that run on the Android mobile operating system, written in Java
• Android Packages (APKs): Contain all the contents of an Android app and installation resources
• Android runs with a multi-user Linux system, where each app is a different user; and a unique Linux user ID is assigned by the system, by default
• Every process has it's own virtual machine for code to run seperately, running it's own Linux process by default

Application Components

• Components exist as their own entity and play specific roles in an app's operation
• Has four types of app components

Four Types of App Components

• Activity: Represents a single screen with a user interface
• Service: Performs background operations
• Content provider: Manages shared app data
• Broadcast receiver: Responds to system-wide broadcast announcements

Others

• Manifest file: Details the components that exists in an app, and is an XML file that uses the filename AndroidManifest.xml
• Intent: An asynchronous message that activates three of the four component types: activities, service, and broadcast receivers, binding individual components to each other at run time
• Four phases of application workflow

Four application workflow phases

• Setup: Install and set up the IDE, and create an Android Virtual Device (AVD); connect hardware devices to install apps
• Development: Set up and develop the Android project and application modules
• Building, Testing, and Debugging: Build the project, debug using the IDE, and test the app using Android SDK tools
• Publishing: Configure the app, build for release, and distribute it to users

Android Development Tools (ADT)

• Android Software Development Kit (Android SDK): Tools for creating, compiling, and packaging Android applications
• Android Debug Bridge (ADB): allows connection to Android virtual or real device(s)
• Gradle: Advanced build toolkit for managing dependencies and custom build logic
• Android Developer Tools (ADT): Plugin for the Eclipse IDE, for quickly setting up Android projects, creating a UI, adding packages based on the Android Framework API

Android Development Tools (ADT) (Cont'd)

• Android Studio: Official IDE for Android App development
• Android Runtime: Managed runtime used by applications and some system services on Android

Setting Up Virtual Devices

• AVD Components
  • Hardware profile: Defines hardware features
  • Mapping to a system image: Defines the Android version
  • Dedicated storage area: Stores device user data and emulated SD card
  • Other options: Specify emulator skin or SD card

Others to setup a virtual device

• Via AVD Manager: Tool in Android Studio for creating and managing AVD's, such as device configurations, for loading to the Android Emulator
• Via Command Line: For stand-alone SDK tools
• Via Emulators: Virtual mobile devices running on a computer

Using Hardware Devices

• Developer Options for Developing Using Android-Powered Devices
  • Debugging over USB: Debugging apps installed on a device connected via USB
  • Bug Report Capturing: Captures bug reports for easier debugging
  • CPU Usage Display: Shows CPU usage to aid in app resource management
  • Debugging Information Drawing: Allows devices to draw debugging information onscreen

How to enable developer options in Android device

• On device, navigate to settings
• Choose About Phone or similar
• Tap Build Number seven times

Managing Projects

• Android Project: Contains everything for the Android app, and follows a structure for correct compilation and packaging
• Module levels of source code files and resources
  • Android Application Module: Contains the app's code, resources, and application settings; Built into a file, the apk
  • Test Modules: Tests the application project
  • Library Modules: Holds shared Android sources and resources
  • App Engine Module: Allows implementation of sending push notifications
• Android Project Files: Provide project-wide settings

User Interface

• User Interface Components
  • User Interface: The face of a program or application that a user interacts with
  • View Object: An object that draws something the user can interact with on the screen
  • ViewGroup Object: Holds other View and/or ViewGroup objects to define the interface layout

Common user interface components

• App Bar (or Action Bar): Provides visual structure and interactive elements that provides dedicated space for app identity, indicating user location, access to important actions, and navigation
• Dialog: A small window that prompts user action before proceeding
• Notifications: Messages displayed outside the application, shown as an icon in the notification area
• Toasts: Small pop-ups that give simple feedback

Layout Types

• Layout: Interface "framework" that arranges content
• Two Ways to Declare Layouts in Android Projects:
  • Declared UI elements in XML: An XML vocabulary quickly designs a UI, similar to HTMl elements in construction.
  • Instantiation of Elements at Runtime: The application can create View and ViewGroup objects with properties that can be manipulated during runtime

Common types of App layouts

Linear Layout- aligns all children in a single direction

• android:orientational attribute: specifies the direction of the layout while android: layout_weight enables you to indicate how much space to occupy Relative Layout - displays child views in relative positions
• Offers certain view properties, such as android: layout_alingParentTop (matches the top edge of current view to the top edge of the parent) and android: layout_toRightOf (positions the left edge of this view to the right of the given anchor of view ID)
• Others include · android:layout_alignLeft · android:layout_centerVertical · android:layout_below List View: displays items in a vertically scrolling list, and it dependent on the swipe function of a mobile device Grid View: displays items in a two-dimensional scrollgrid, the layout is similar to the Home menu of most Android devices Input Controls

Input Controls

• Allows a user to enter a character, number, email address or sentence into an app

Buttons properties

• Button Classes: contains a text, icon or both to generate their own set of events that can be handled
• ImageButton Calsses
• Buttons and icons with both

Others

Text Fields: Has enables capabilities for texts, command of cut, copy and paste Checkboxes: allows multiple options from sets of choices Radio buttons: one option from a set of choices Toggle buttons: enables/disables settings Spinners: quick way to choose values Pickers: select time and date

Android App Activities

• This is an application component with a single screen with a user interface
• Each has one connection from the others, which starts other activities for different actions

Activity states

• Running/Resumed: The activity is in the foreground
• Paused: Another activity is in the foreground but is still visible
• Stopped: The activity is in the background

Workflow, lifetimes, etc.

• Callbacks (methods)
• Visible lifetime: Happens between the call to onStart() and the call to onStop()
• Foreground lifetime: Happens between the onResume() and the call to onPause().
• Fragments: Modular section of an activity with its own lifecycle
• Three essential callback methods in order to be implemented
• onCreate()
• onCreateView() _ onPause()