Picker is a very common UI control. In order to capture user input we have to listen to ’SelectedIndexChanged’ event, which unfortunately behaves differently on iOS and Android:

Imagine you have a lovely DB first approach in place. There is a table “Fruits” with a column “WikiLink”. This column is getting populated on insert, using a trigger on the DB level. Can you spot “the” problem here?

Model state validation is easy with DataAnnotations. However, you will find repeating the next line of code very soon:

Using Entity Framework is extremely easy and straight forward unless you have a large amount of entities and business rules to apply. You are lucky if you have a code first approach, however some times database first approach is in place and there are some limitations. For example, as the DbContext is autogenerated using T4, it is hard to introduce general behaviours, like updating CreatedAt, UpdatedAt and DeletedAt properties globally upon saving.

Implementing INotifyPropertyChange is pretty straightforward. Usually, you create a base ViewModel class which implements it and which usually contains RaisePropertyChanged method:

What is great about Xamarin.Forms? XAML of course! Especially if you are familiar with it from WPF / Silverlight times. However, the experience with XAML in Xamarin.Forms is totally different. Unfortunately, you will not have such a great intellisense, by default you will have to discover typos in XAML at runtime, no visual editor (yet) and without preview. I have been using VS 2017 on Windows and VS For Mac on macOS, in both cases problems listed above exists.

Problem

Show hh:mm:ss picker on iOS using Xamarin.Forms.

Problem

Legacy backend API endpoint returns JSON with units in an uncommon manner.
Instead of returning the measurement system “imperial” or “metric” it returns “kgs” or “lbs”.

Following Local Databases Xamarin guide in order to add SQLite database to a Xamarin Forms project I spent quite some time on adding the “SQLite.Net PCL” nuget package. It failed with the next message: