Question: Now I have something like this:

```
<input type="text" ng-model="cell.location">

```

What I want is while you put 'ABC' in this field, this field will become disabled status, I know I can put a boolean param to control it via its controller.

However what I expect is something like this:

```
<input type="text" ng-disabled="{{cell.location = 'ABC'}}" ng-model="cell.location">

```

Which is clearer and simpler, unfortunately this approach doesn't work as expected, it will assign 'ABC' to this field rather than disable it. is that possible to implement in this kind of way? 

Thanks.

Answer: 
Found this error at Release build, yet not in Debug build.

For Xamarin + VS, TLS 1.2 can be set in Android Project Properties (right click on your Android Project > Properties on bottom) > Android Options > scroll to bottom, click Advance > bottom, SSL/TLS Implementations. There you found Native TLS 1.2+.
Currently TLS 1.2 is supported by Mono [release](http://www.mono-project.com/docs/about-mono/releases/4.8.0/) 4.8.0