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    • What is Zebble?
    • Structure of a Zebble solution
    • Zebble Designer (UWP)
    • Installing - Introduction
    • Change log
    • Introduction
    • ViewModel development
    • VM.EXE
    • View development
    • Dialogs
    • Lists and Collections
    • Tips and shortcuts
    • List views
    • ViewModel testing
    • Automatic Views
    • View development process
    • Hello World - Core Concepts
    • Layout: Sizing & Positioning
    • Event handling
    • Navigation
    • Alerts, Dialog, Prompt and toast
    • View lifecycle
    • Managing Files & Resources
    • Config & Debugging
    • Forms
    • Page templates
    • Device API
    • Animations
    • Web Api - Part 1 (reading data)
    • Web Api - Part 2 (post and delete)
    • Web Api - Part 3 (server vs client domain model)
    • Gesture events
    • View class
    • Zebble Markup (.zbl files)
    • Data Binding and MVVM
    • Stack class
    • Sizing and positioning
    • Layout examples
    • ScrollView class
    • Page class
    • Styling in Zebble
    • CSS property mapping to Zebble
    • Supported selectors
    • Zebble CSS: Under the hood
    • Inline styling
    • CSS real-time updates
    • Dynamic expressions in CSS
    • Gradient background colours
    • CSS Pseudo-classes support
    • Using Bold and Light Fonts in Zebble
    • Rotation in Zebble
    • Using custom fonts in Zebble
    • Flashing on tap using AutoFlash
    • Button
    • Carousel class
    • Checkbox class
    • DatePicker
    • Drawing class
    • FilePicker class
    • Grid class
    • IconButton class
    • ImageView
    • ItemPicker class
    • ListView & Grid classes
    • OptionsList
    • SearchInput class
    • Slider class
    • Switch class
    • Tabs Class
    • TextInput class
    • TextView
    • TimePicker
    • TreeView
    • Waiting Indicator
    • WebView class (displaying html)
    • C# Methods and Properties Of UI Components
    • Nav.Forward() vs Nav.Go()
    • Passing parameters to the destination page
    • Going Back
    • Showing Popup pages
    • Waiting class
    • Hardware Back button (e.g. Android)
    • NavigationBar class
    • Tabs class
    • Caching (pages)
    • Navigation without event handler
    • Use the Windows version
    • Logging messages for Debugging
    • Debugging Zebble/Plugin
    • Exception handling in Zebble
    • Debugging layout and styles
    • Zebble Device API
    • Device.Screen and orientation (landscape | portrait)
    • Code that should run on a specific platform
    • Using Lamp (aka Flash, LED and Torch)
    • Using Compass (Smooth compass)
    • Using Accelerometer (device angle)
    • Using Gyroscope (device motion speed)
    • How to Vibrate the device?
    • Launching the device browser
    • Finding device model and manufacturer
    • Responding to System events
    • Handling device shake event
    • Permissions
    • Permissions declaration (manifest files)
    • Sharing
    • Prompt for rating the app
    • Finding if Internet connection is available
    • Device messaging (Make a phone call, send SMS or Email)
    • Showing a local notification
    • Copying to Clipboard
    • Accessing device contacts
    • Reading and writing into Gallery (albums)
    • Playing & Recording Audio
    • Cache and temp files and folders
    • C# async / await
    • Understanding Zebble Threading
    • Debugging - the StackTrace problem
    • Not awaiting (running in parallel)
    • Timer (interval / scheduled running)
    • Post-render changes to the UI (dynamic)
    • Introduction of Geo location
    • Map & Location Services
    • Launch directions to a location (external)
    • Getting current Location
    • Tracking user location
    • Device.Media: Taking and picking photos
    • Playing an audio file
    • VideoPlayer class
    • Augmented reality
    • Recording audio
    • Virtual Reality
    • Speech Recognition
    • Recording or picking video
    • Playing remote videos in iOS
    • Text to speech
    • Introduction to the importance of Mobile Testing
    • Why and what to test
    • Testing mobile apps on different devices
    • Testing mobile apps
    • Xamarin Profiler
    • Performance optimization
    • Moving a view to another container at run-time
    • Attaching custom data (tag) to objects
    • Saving a view as image
    • Naming best practices
    • Fastest way to update your nuget package
    • Tips for Clean and Brief code
    • Splash screen and icon generation
    • Advice for passing Approval
    • Options for iOS app distribution
    • Test Release (internal and UAT)
    • Application Icons in IOS
    • Submitting to App Store
    • Releasing to App Store
    • Crash reporting
    • Optimized Release Build
    • Android - Generating an APK for manual installation
    • Payment (subscriptions & in-app purchases)
    • Introduction to push notifications
    • Registration process (App)
    • Push notification setup - iOS
    • Push notification setup - Android
    • Push notification setup - Windows
    • Sending a push message from the web app
    • Introduction
    • Connecting Zebble to Web API
    • Installation
    • Creating an API class
    • GET APIs
    • Calling a GET API (in the mobile app)
    • POST, PUT, PATCH and DELETE APIs
    • Domain Model
    • Web API and Authentication
    • Versioning
    • Uniquely identifying installations (token)
    • Settings file: config.xml
    • Standard Zebble settings
    • Login/Register with Facebook
    • Creating a composite component / plugin
    • Creating a Zebble component using Html and Javascript
    • CustomRenderedView: Third-party native components / plugins
    • Mapbox
    • Naming considerations
    • Random problems?
    • Display Keyboard for Visual Studio Android Emulator
    • iOS goes mad?
    • Configuring a Windows phone for ad-hoc testing
    • Fixing Error DEP0001 : Unexpected Error: -2147009287 while deploying Windows UWP app on device
    • Fixing Error DEP0001 : Unexpected Error: -1988945906 while deploying Windows UWP app on device
    • Unable tp Connect to the Mac agent from Visual Studio
    • Can't connect to the Mac agent from Visual Studio?
    • Choosing the CPU architecture
    • Zebble CLI
    • How to add a Device API to Zebble source?
    • About Automated UI testing
    • What should we test in mobile applications?
    • Creating an Automated UI Test in Zebble



Caching (pages)


A very effective way to make your apps faster is by caching the pages where possible. You can achieve that in Zebble via either of the following methods:

  • In the code behind of your Zebble page, add [CacheView] attribute:
    [CacheView]
    partial class MyPage
    {
       ....
    }
  • Or, in the ZBL markup, add z-cache="true":
    <z-Component z-type="MyPage" .... z-cache="true">
       ...
    </z-Component>

How is it used in Zebble?

Normally when you navigate away from a page, it is disposed of by the system as soon as it gets a chance (usually in less than a second after leaving the page).

When you enable caching for a page, it will no longer be disposed of when navigating away from that page. Instead, it will remain inside a static stack in the Nav class.

When you navigate to a page, if it does not exist in the cache, it will be created and rendered before the page transition animation starts. If it does exist in the cache, however, then the previously created and rendered page will be displayed and the transition animation will start immediately.

Cached page lifecycle

The standard view lifecycle events such as OnInitializing, OnInitialized, OnPreRender, OnApplyingStyle, etc are only invoked when a page is created for the first time. If you navigate back to a page that was previously cached, those events will not be fired.

The only event that will be fired is the Shown event, which you can handle by using the WhenShown(...) method.

Caching v.s. Nav parameters

For each cached page, there will be a maximum of one instance created and used by the Nav cache management system. If your cached page doesn't use any navigation parameters, then everything is fine. For example:

await Nav.Go<ACachedPage>();

But how about when you navigate to a cache-able page that accepts a parameter? Consider a cache-able page that shows the details of a product. When you navigate to it, you will usually need to pass the product parameter to display:

await Nav.Go<ACachedProductViewPage>( new { product = myProduct } );

On the target page then you will be using the product data to populate the UI. For example, you might have the following code:

public override async Task OnInitializing()
{
    await base.OnInitializing();
    await InitializeComponents();
    
    LoadProductDetails();
}

void LoadProductDetails()
{
     var product = Nav.Param<Product>("product");
     ProductTitle.Text = product.Name;
     ...
}

But remember there is always only one instance of that page cached, so if you navigate to the same page with another product as nav parameter, the new parameter will be ignored and the page will still show the old product's details.

To solve that problem, you need to make sure that if a page is cached, it can also update itself upon being Shown again:

public override async Task OnInitializing()
{
    await base.OnInitializing();
    await InitializeComponents();
    
    LoadProductDetails(); // We keep this line for a slightly better first-time loading experience.
    await WhenShown(() => LoadProductDetails());
}

Cleaning up the cache

In case you need to remove all pages from the cache, you need to call the following method:

Nav.DisposeCache();For example, if your app has a Logout functionality, it's a good idea to clear the cache to prevent unintended security issues.




‹
Zebble is a product of Geeks Ltd , a software house based in London, UK. All rights are reserved.

Telephone: +44 (0)845 643 6229

Email: hello@zebble.net

Address: 66a London Road, Morden

Greater London, United Kingdom, SM4 5BE

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