Posts

Introduction

It is quite strange that you can’t easily detect if software keyboard is visible or not on Android. Because of that, it is also complicated thing to do in Xamarin.

Introduction

In Xamarin if you want to use many Android native service/mechanism you have to implement it in Activity class. Or at least that is how Xamarin documentation wants you to do it.

Introduction

This article is builds on topics and solutions introduces in ViewFactory for Xamarin application and Xamarin Master-Detail Page articles. It shows method for easier navigation and use of services via IoC in Xamarin application. Knowledge from previous examples is not necessary, but makes this article bit easier to understand.

Reflection.Emit is very powerful tool. It creates IL code and since C# is converted into IL too, we have the same functionality as in C# and even more. It is very powerful and at the same time very complicated. Because of that it is worth to discuss how and for what it should be used. One idea is to create dynamic code with automatic implementations of interfaces - proxy types.

This is third article in series, that explains how to create delegates for public and non-public members of public, non-public or not known in compile-time types. If you are not familiar with previous articles and looking for detailed explanation of how delegates works, how they are created and why, I strongly encourage you to read first two. If you are just looking for a way to create delegates for methods or constructors it is not necessary. Code with new features and with bug fixes is available on GitHub and as Nuget package.

This is second article in series, that explains how to create delegates for public and non-public members of public, non-public or not known in compile-time types. If you are not familiar with previous article and looking for detailed explanation of how delegates works, how they are created and why, I strongly encourage you to read it first. If you are just looking for a way to create delegates for methods or constructors it is not necessary. Last article in series you can find here . Code with new features and with bug fixes is available on GitHub and as Nuget package. In previous article and first one in series, we covered:

1. Static
   1. Properties
   2. Fields
2. Instance
   1. Properties
   2. Fields
   3. Indexers

Now it is time to cover following members.

1. Static
   1. Methods
2. Instance
   1. Methods
   2. Constructors

This article is first part of the series of three. Next ones you can find here and here . Code for all three articles, with new features and bug fixes is available on GitHub and as Nuget package.

Why not Reflection?

If you working with .NET and C# (probably other languages too), at some point, you will have to write more advanced and generic code, that i.e. reads all properties of a type, searches for attributes, etc. Or maybe you want to call some private method or property? It is not that rare to use some internal mechanism of framework or library. Usually, the first solution involves Reflection. But the thing is: Reflection is slow. Of course, it is sufficient if you need to use Reflection rarely and it is not the main code of the application. If it is used more often at some point, you will probably try to optimize it. And now is the fun part: how to do it?

First things first - Why?

First of all I do not like how creating of views and navigation works in Xamarin. There is much boilerplate needed to just navigate from one page to another. Typically like in Xamarin documentation we have to obtain INavigation interface instance, create instance of a new page, create instance of view model and all dependencies it requires. When you page do not require view model things are real easy and Xamarin sample is just enough.

This article as previous ones (Frame With Padding , Frame Outline Problem , Inheritance from Implicit Styles ) also will be about Xamarin. This time we will inspect Master-Detail page control/mechanism. You can find official documentation for this control here . Quick spoiler: I never used this in any production application. Why? I will explain. Whole article will be to explain why this is just not worth your time. In this and subsequent articles I will introduce much better solution.

Next article about bugs in Xamarin will touch topic of Styles. Styles for all of controls not only Frame (and if you wondering why Frame you should check first two articles about Xamarin here and here) . First of all if you are using Styles in Xamarin you probably know how to define implicit styles. If not here is a sample:

<Application.Resources>
  <ResourceDictionary>
    <Style TargetType="Label">
      <Setter Property="FontSize" Value="45" />
    </Style>
  </ResourceDictionary>
</Application.Resources>

This is another article in mini series of Xamarin bugs and workarounds for them :) Previous one you can find here . This one is again about Frame control. I promise that another one will be about something else B) Issue can be observed when you bind BackgroundColor property of Frame control and something will trigger change of view model source property binded to background color.

If you are a bit advanced with Xamarin you should already now that there is possibility of styling your controls almost like in WPF. Almost, because there is a few strange bugs involving this. For example there is a problem with styling a Padding property in Frame. Consider following Xaml of Xamarin application (I tested it in Android):

In on of my projects I had make an interface between database and web service in C# code. One of problem I had to face was need to cast strings to enumerable types, because of simple fact that database have no idea what is an ’enum’. Yes simplest mapping between an enumeration and database type is integer. It is simplest but in my idea not best. For example I really do not remember (or do not WANT to remember) what is the meaning of 4 integer value in case of package shipment status.

What I really like in Visual Studio as development environment is code snippets. Well actually probably other IDE have something very similar but I do not have much of a choice in that matter as C# developer :) Anyway this feature is really useful. For example while refactoring I very often use if surround snippet.

In this rare times when I was writing code that suppose to create large string from smaller chunks and with some non string parameters I was using StringBuilder class of course. Of course because string adding, or string concatenation is very costly when talking about memory utilization. It is because every time you do this:

var text = "Hello world!"+ "n"+ "How are you?";

new string is created for every ‘+’ operation in memory. Not a best way of doing strings creations. StringBuilder is better because it do not creates strings until you call .ToString method of StringBuilder class.