xamarin.forms features that will make your life easier
TRANSCRIPT
Xamarin. Forms Features That Will Make Your Life Easier: DependencyService & MessagingCenter
Andres Castro
My Background
Andres Castro• ASP.NET MVC
• ASP.NET WEBFORMS
• Web Services
• Xamarin
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Dependency Service
What is it?
The Xamarin.Forms Dependency Service is a simple
dependency resolver that simplifies how platform specific
features are implemented.
Basically, it allows you to register classes which will then be
pre-initialized for you upon request. It removes the need for
you to “new” every time you need to use that class.
Dependency Service
How does it work?
There are 3 steps necessary to successfully using the
dependency service.
1. Create an interface that will define how each platform
should be implemented.
2. Register each platform-specific implementation of the class
above.
3. Use the implemented interface using
DependencyService.Get<T>
Dependency Service
Creating the Interface
As an example, I will be creating a interface that allows you to
open the Phone Dialer from within your app.
Dependency Service
Registering the Android Implementation
Dependency Service
Registering the iOS Implementation
Dependency Service
Using the Code
Messaging Center
What is it?
The Xamarin.Forms Messaging Center allows you to send and
receive “Messages” without knowing who they are going to or
who they are coming from.
It is very similar to using Event Handlers, the only difference is
that you are hooking into the Messaging Center.
Messaging Center
How does it work?
There are three parts to using the Messaging Center
1. Subscribe – Subscribes the messaging center to listen to a
certain message. You can then perform an action based on
that message.
2. Send – Sends a message through the messaging center so
that any subscribed classes receive the message.
3. Unsubscribe – Stops listening to any messages that might
come through.
Messaging Center
Example
Lets extend the existing Phone Dialer Example to navigate us
back, which will take us to a new page after the call code has
executed.
Messaging CenterLet’s first create a message class that will help to wrap data
we want to send.
Messaging Center
Subscribing to the Message
Messaging Center
Sending the Message
Recap
– Covered what the Dependency Service is and how to
implement it.
– Saw how to call platform specific code using the
Dependency Service.
– Covered what the Messaging Center is and how to
implement it.
– Used the Messaging Center to implement navigation inside
the app.
Dependency Service & Messaging Center
References– http://developer.xamarin.com/recipes/android/fundam
entals/intent/launch_the_phone_dialer/
– http://developer.xamarin.com/recipes/ios/shared_reso
urces/phone/dial-phone-uri/
– http://developer.xamarin.com/guides/cross-
platform/xamarin-forms/dependency-service/
– http://developer.xamarin.com/guides/cross-
platform/xamarin-forms/messaging-center/
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