deep dive xamarin.android

Ben Bishopben@rendr.io

A DEEPER DIVE INTO XAMARIN.ANDROID

for code/slides...@benjamminstl

@rendrstl

Who Am i?• My name is Ben Bishop (Twitter:

@benjamminstl)

• I grew up in a small rural town of Indiana

• Went to Purdue University

• Now lives in Saint Louis

• Been independent for 4+ years

• Worked at an agency for 5 years, 1 year at TMG

my new companyhttp://rendr.io

WHAT IS A XAMARIN?

“The best damn mobile team,building the best damn mobile platform.”

What is Mono?• Mono 1.0 was released on June 30, 2004

• “The Mono runtime contains a code execution engine that translates ECMA CIL byte codes into native code and supports a number of processors: ARM, MIPS SPARC, PowerPC, S390 , x86, x86-64 and IA-64 for 64-bit modes.”

• Also has support for LLVM

• Runs on Linux, OSX, Windows, PS3, XBox 360, Wii

How does Mono Work?“Xamarin compiles your app to a native binary, not cross-compiled, and not interpreted.”

ART (Android RunTime) is an experimental runtime that could replace Dalvik. ART uses

Ahead of Time compilation instead of JIT (like iOS)

Code StructureBy only having to write core code once, more time

can be spent tuning the UI per platform.

must have componentsComponents that keep you from having to write

platform specific code.

xamarin.mobileA component that helps abstract your code for

location, photos, and contacts across all platforms.

Xamarin.SocialA component that helps abstract your code for

App.Net, Twitter, Facebook, and Flickr

xamarin.authMakes OAuth suck less.

DataRestSharp, SQLite.NET, and JSON.net help you

store and retrieve data for your app.

Android componentsGoogle Play Services allows your app to interface with the PlayStore. Android support helps make

your Android app backwards compatible.

Frameworks

https://github.com/MvvmCross/MvvmCross

https://github.com/benbishop/MonkeyArms

anatomy of an Android app

Android Manifest.xml

Edit App Name & Package, Icon, Version #, Min and Target Android SDKs, Permissions

specify supported screens

http://developer.android.com/guide/topics/manifest/supports-screens-element.html

Pro tip: need for speed

You can specify hardware acceleration for the app or for specific activities. http://developer.android.com/guide/topics/graphics/hardware-accel.html

More activity options

http://developer.android.com/guide/topics/manifest/activity-element.html

Activities

Activity Lifecycle

Activity Lifecycle

Activity Lifecycle

lifecycle in use

another example

OnResume and OnPause are good placesto do assignment and release.

declaring activity behavior

In this case, InitialActivity is our splash/loading screen.

layouts

Anatomy of a layout

includes

layouts for orientations

By creating a directory “layout-land,” Activities will use this as content when orientation changes.http://docs.xamarin.com/guides/android/application_fundamentals/handling_rotation/

layouts for screen sizes

Relying on naming conventions you can specify layouts to be used for screen widths. “layout-large” is for Android

apps below API-13, “layout-swXXXdp” is for 13 and above.

How layouts are connected to your code

Strings.xml

How to connect strings.xml to your code

You can link via layout xml or use “GetString” from your Activity.

string array

This can be used as a data provider for a spinner.

localization

More folder name magic!

More value resource typesBoolXML resource that carries a boolean value.

ColorXML resource that carries a color value.

DimensionXML resource that carries a dimension value. IntegerXML resource that carries an integer value.

Integer ArrayXML resource that provides an array of integers.

Typed ArrayXML resource that provides a TypedArray (which you can use for an array of drawables).

Style.xml

declare reusable styles

Units of measurepxPixels - corresponds to actual pixels on the screen.

inInches - based on the physical size of the screen.

mmMillimeters - based on the physical size of the screen.

ptPoints - 1/72 of an inch based on the physical size of the screen.

dpDensity-independent Pixels - an abstract unit that is based on the physical density of the screen. These units are relative to a 160 dpi screen, so one dp is one pixel on a 160 dpi screen. The ratio of dp-to-pixel will change with the screen density, but not necessarily in direct proportion. Note: The compiler accepts both "dip" and "dp", though "dp" is more consistent with "sp".

spScale-independent Pixels - this is like the dp unit, but it is also scaled by the user's font size preference. It is recommend you use this unit when specifying font sizes, so they will be adjusted for both the screen density and user's preference.

Connect style to view

Drawables

Using a PNG

PNGS FOR STATES

vector drawable

alternative drawables

Using folder naming conventions will tellAndroid what version of the drawable to use

MainApplication

BOOTSTRAP/INIT

Class will be instantiated on app startup.

sending intents

receiving intents

simple listview

Create and assign adapter

Grouped ListView

Setup list of data.

Assign an adapter

In our Adapter, we collapse unused TextViews

FragmentsAndroid 3.0+

Set layout of Activity

init tab fragments

the fragment

fragment lifecycle

Fragments are important

Fragments promote code reuse.

custom views

Month Layout

Week Layout

notated cell

OnDraw

UpdateSwatches

Calendar month activity

Update calendar

Update week labels

when month events set

Updating cell swatches

parting thoughts

experiences- The Android SDK is substantially more robust (complicated?) than iOS

- Device fragmentation is challenging (TestCloud)

- Emulators suck. Use a device instead.

- Not as prescriptive in UX/Design

- The more innovative (but not as polished) platform.

thank you!