Is it possible to retrieve AppId then pass this as the parameter in Widget?

Is that possible to retrieve AppId then pass this as the parameter in Widget? 

For instance, the code is very simple:

<iframe src='https://feiqs.visual.visualintelligence.co.nz/single/?appid={{settings.AppID}}&obj={{settings.ObjectID}}&opt=nointeraction&select=clearall' style='border:none;'></iframe>

This appid is set in property panel and pass to the widget HTML. 

The purpose is to open different app whenever the user select different appid.

For Widget, Qlik Sense has three available properties to be bound to the HTML or CSS templates.  Please find details from the link http://help.qlik.com/en-US/sense-developer/September2017/Subsystems/Extensions/Content/Widget/widgets-data-binding.htm,

Title {{settings.title}}

Subtitle {{settings.subtitle}}

Footnote {{settings.footnote}}

But custom properties also can be used and past to a widget but that has to be through the property panel.   This links contains the customer properties information.  
http://help.qlik.com/en-US/sense-developer/September2017/Subsystems/Extensions/Content/Howtos/working-with-custom-properties.htm.

But the properties to be used in Widget is limit.  The supported way of using the appid etc would be to use extensions. Widgets are restricted to make it easier for users to develop and maintain them.  The advanced feature should always consider to use extension.  

The calls to use is in the Capability API and are as follows but can only be used in a Mashup or extension.

To receive a list of all applications and the appid by using this call

getAppList method ‒ Qlik Sense Developers

To get all objects in an app by using:

getAppObjectList method ‒ Qlik Sense Developers

To get an object using the visualization api by using

get method ‒ Qlik Sense Developers