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Mastering Cross-Platform Development with Xamarin
Mastering Cross-Platform Development with Xamarin

Mastering Cross-Platform Development with Xamarin: Master the skills required to steer cross-platform applications from drawing board to app store(s) using Xamarin

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Mastering Cross-Platform Development with Xamarin

Chapter 2. Memory Management

This chapter investigates how memory is managed on iOS and Android with Xamarin runtime. Whilst drawing parallels to the .NET platform, it will provide examples of memory management problems and issues that can cause leaks, and also look at useful patterns that can help developers save valuable resources. This chapter is divided into the following sections:

  • Application Component lifecycle
  • Garbage collection
  • Platform-specific concepts
  • Troubleshooting and diagnosis
  • Patterns and best practices

Application Component lifecycle

Each platform in the Xamarin ecosystem has certain processes and states that the applications go through during their execution lifetime. Developers can implement certain methods and subscribe to lifecycle events such as application start, suspension, termination, and backgrounding to handle much needed application state and release resources which are no longer required.

Activity lifecycle (Android)

In Android applications, contrary to the conventional application development model, any activity can be the access point to the application (as long as it is designated as such). Any activity in the application can be initialized at start-up or can be resumed directly when the application is resuming or restarting from a crash.

In order to manage the lifecycle of the activities, there are distinct states and events which help developers organize memory resources and program features.

Active/Running

An activity is said to be in the active state when an application...

Garbage collection

Garbage collection (GC) is one of the most effective automated memory management techniques on modern application development platforms. In simple terms, with automated garbage collection, memory resources are allocated for objects used by the application and reclaimed for resources no longer needed by the application.

Note

In spite of the fact that garbage collection, as an automated process, takes over the burden of managing memory allocations, it can have a significant impact on performance. This performance handicap is one of the main reasons why there is no garbage collection mechanism on the iOS platform.

In theory, GC is responsible for reclaiming memory resources occupied by runtime elements that cannot be reached by the current executing application. However, this mechanism cannot always identify these unreachable resources correctly and/or have unexpected results while purging the identified memory pointers.

Memory leaks occur when an application fails to identify...

Platform-specific concepts

In order to understand the memory management techniques and pitfalls, one must understand some platform-related concepts. Even though Xamarin provides an almost platform agnostic development experience, iOS and Android platforms deal with memory allocations and references slightly differently from .NET CLR and each other.

Object reference types

Referred objects can be classified according to application needs. This classification helps the garbage collector decide whether the memory allocation can be released for the referred objects.

A strong reference protects the object from being "garbage collected". A referred object is said to be strongly referenced/reachable when the class instance is directly used by the current execution context.

Weak references can be used for class instances when the need for the reference does not interfere with garbage collection. When the referred object is weakly reachable, the dependent section of code has to check whether...

Troubleshooting and diagnosis

Profiling is the term used to describe the dynamic system analysis while the target application is running. Profilers generally collect data about metrics such as CPU utilization, framerate values, and most importantly data about memory allocations. Especially with Xamarin projects, since we are dealing with multiple platforms, profiling becomes an important part of testing and diagnostics.

There are numerous tools that one can use to profile memory usage on Xamarin projects, Xamarin Profiler being the only one that can be used both for Xamarin.iOS and Xamarin.Android applications.

Xamarin Profiler

Xamarin Profiler is the newest addition to the Xamarin Suite. This profiler has the advantage over other platform-specific applications since it can be run either on OS X or Windows targeting Xamarin.Android or Xamarin.iOS applications.

Xamarin Profiler

Figure 2: Xamarin Profiler

It was designed to give developers almost real time (depending on the sampling rate) information about the...

Patterns and best practices

While dealing with managed runtime and garbage collection, there are certain patterns and anti-patterns developers must be careful with. If not handled properly, both managed and native objects can produce noncollectable traces, which in turn can cause memory leaks and unnecessary resource consumption.

Disposable objects

The resources managed by the garbage collector are generally limited to memory allocations. Other resources like network sockets, database handles, UI elements, and file/device descriptors need to have additional definitions or mechanisms.

In managed runtime, these object resources can be cleaned up in two different ways. The first, less efficient, unpredictable way is to implement a destructor/finalizer. With a finalizer implementation, once the garbage collector decides the object is no longer strongly reachable, the resources such as network sockets can be disposed. However, finalizable objects have to wait for the following GC cycle to be cleaned...

Application Component lifecycle


Each platform in the Xamarin ecosystem has certain processes and states that the applications go through during their execution lifetime. Developers can implement certain methods and subscribe to lifecycle events such as application start, suspension, termination, and backgrounding to handle much needed application state and release resources which are no longer required.

Activity lifecycle (Android)

In Android applications, contrary to the conventional application development model, any activity can be the access point to the application (as long as it is designated as such). Any activity in the application can be initialized at start-up or can be resumed directly when the application is resuming or restarting from a crash.

In order to manage the lifecycle of the activities, there are distinct states and events which help developers organize memory resources and program features.

Active/Running

An activity is said to be in the active state when an application...

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Key benefits

  • Develop your Xamarin development skills with this comprehensive guide on various patterns and features so you can create elegant and high-quality applications
  • Create adaptive user interfaces on separate platforms without compromising the user experience and platform identity
  • Implement application lifecycle management concepts to manage and finalize cross-platform projects and efficiently collaborate with others

Description

The main goal of this book is to equip you with the required know-how to successfully analyze, develop, and manage Xamarin cross-platform projects using the most efficient, robust, and scalable implementation patterns. This book starts with general topics such as memory management, asynchronous programming, local storage, and networking, and later moves onto platform-specific features. During this transition, you will learn about key tools to leverage the patterns described, as well as advanced implementation strategies and features. The book also presents User Interface design and implementation concepts on Android and iOS platforms from a Xamarin and cross-platform perspective, with the goal to create a consistent but native UI experience. Finally, we show you the toolset for application lifecycle management to help you prepare the development pipeline to manage and see cross-platform projects through to public or private release.

Who is this book for?

This book is ideal for those who want to take their entry–level Xamarin mobile development skills to the next level to become the go-to person within their organization. To fully understand the patterns and concepts described, you should possess a reasonable level of knowledge about the core elements of Xamarin and cross-platform application development with it.

What you will learn

  • Configure your environment for cross-platform projects with Xamarin
  • Gain memory management skills to avoid memory leaks and premature code cycles while decreasing the memory print of your applications
  • Employ asynchronous and parallel patterns to execute non-interactive and non-blocking processes
  • Create and use SQLite databases for offline scenarios
  • Integrate network resources with cross-platform applications
  • Design and implement eye-catching and reusable UI components without compromising nativity in mobile applications
  • Manage the application lifecycle of cross-platform development projects
  • Distribute Xamarin applications through public or private channels
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Publication date : Mar 31, 2016
Length: 390 pages
Edition : 1st
Language : English
ISBN-13 : 9781785285684
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Product Details

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Length: 390 pages
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ISBN-13 : 9781785285684
Vendor :
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Table of Contents

13 Chapters
1. Developing with Xamarin Chevron down icon Chevron up icon
2. Memory Management Chevron down icon Chevron up icon
3. Asynchronous Programming Chevron down icon Chevron up icon
4. Local Data Management Chevron down icon Chevron up icon
5. Networking Chevron down icon Chevron up icon
6. Platform Extras Chevron down icon Chevron up icon
7. View Elements Chevron down icon Chevron up icon
8. Xamarin.Forms Chevron down icon Chevron up icon
9. Reusable UI Patterns Chevron down icon Chevron up icon
10. ALM – Developers and QA Chevron down icon Chevron up icon
11. ALM – Project and Release Management Chevron down icon Chevron up icon
12. ALM – App Stores and Publishing Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
(4 Ratings)
5 star 25%
4 star 25%
3 star 0%
2 star 25%
1 star 25%
Amazon Customer Nov 26, 2016
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Excellent reference. Clear and concise examples...
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Naeem Feb 11, 2017
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
Good book.
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Amazon Customer Apr 21, 2017
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
The book describes some aspects of multiplatform programming but it is not written well. It is bad readable, bit chaotic, code examples without context.
Amazon Verified review Amazon
Kmustang Nov 10, 2016
Full star icon Empty star icon Empty star icon Empty star icon Empty star icon 1
This book is a waste of paper, it will not help you master ANYTHING. For example, the entire topic of Custom Renderers, a somewhat complex feature to help with platform-specific implementations, is allocated approximately one page of this book. The overview in the online Xamarin documentation is orders of magnitude deeper than what this book provides. At best you could call this a Cross-Platform Development with Xamarin high-level overview.
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