The most common cause of these symptoms
The most likely cause of this problem is the following known error: https://bugzilla.xamarin.com/show_bug.cgi?id=25811
Explanation
The problem with this error is that the Xamarin.Forms template uses a bad default setting for the iOS project in Visual Studio Configuration Manager.
The configuration manager works by telling Visual Studio which projects you want to create and / or deploy at the same time in the configuration that you are using at that time.
For example; when you create your Android project in Forms, the configuration manager guarantees the inclusion of a common project; otherwise it will not work, or you will have to build it separately, etc. etc. (i.e. real pain.)
Typically, Visual Studio is not automatically able to "know" which projects you want to include in all your configurations; you must tell him to enable (some libraries) with (some applications); etc. manually.
How to fix it
Screencast: http://www.screencast.com/t/zLoQOpEn
- Go to "Build -> Configuration Manager"
- Select the configuration (s) you want to configure (e.g. Debug | iPhoneSimulator, Release | iPhone)
- Make sure your shared library projects are included in the platform configuration. (You can ignore the grayed out "Expand" checkbox, which are processed automatically)
Why is this a mistake
So, this is not a mistake in the fact that the configuration manager does not work correctly for iOS projects, but when creating a new application in the form template, the poor default setting for iOS projects is used. He must “know” to enable a common project in the default iOS configuration.
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