title: Entry binding to int? in Xamarin Forms
body: <p>I have a simple entry in Xamarin Forms:</p>
  
  <pre><code>&lt;Entry Text="{Binding Number, Mode=TwoWay}" Placeholder="Number" Keyboard="Numeric" /&gt;
  </code></pre>
  
  <p>In ViewModel there is property:</p>
  
  <pre class="lang-cs prettyprint-override"><code>    private int? _number;
      public int? Number
      {
          get { return _number; }
          set
          {
              if (SetProperty(ref _number, value))
              {
                  OnPropertyChange(nameof(Number));
              }
          }
      }
  </code></pre>
  
  <p>I enter number in Entry and press button, but in button clicked procedure - Number is still null. What am I doing wrong?</p>