[iOS][Fallback] Custom Renderer fallback handling fails

[Aditya0603]

Platform

• iOS

Author or host

Host (Teams)

Version of SDK

1.2.5

Details

Fallback rendering for custom renderer fails while fallback element is text.

Steps -
1/ create a custom renderer for ACRMedia
2/ Throw a ACOFallbackException in render

try the below JSON

{
"$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
"type": "AdaptiveCard",
"version": "1.1",
"fallbackText": "This card requires Media to be viewed. Ask your platform to update to Adaptive Cards v1.1 for this and more!",
"body": [
{
"type": "Media",
"poster": "https://adaptivecards.io/content/poster-video.png",
"sources": [
{
"mimeType": "video/mp4",
"url": "https://adaptivecardsblob.blob.core.windows.net/assets/AdaptiveCardsOverviewVideo.mp4"
}
],
"fallback": {
"type": "FactSet",
"facts": [
{
"title": "Fact 1",
"value": "Value 1"
},
{
"title": "Fact 2",
"value": "Value 2"
}
]
}
}
]
}

[shalinijoshi19]

@nesalang can you take a look here? Thanks for reporting @Aditya0603 / @VikrantSingh01

We have acknowledged this issue report. Please continue to follow the issue for updates/progress/questions. @matthidinger / @dclaux / @RebeccaAnne / @paulcam206 FYI.

[jwoo-msft]

@Aditya0603 ,

there are two apis to register custom renderers

1. setBaseCardElementRenderer
   Used to override the behavior of the renderers that render known elements.
   This is the one that should be used for this issue since Media type is a known adaptive cards element.
2. setCustomElementRenderer
   Used to add a new type that is currently unknown to adaptive cards scheme, and it requires to register a corresponding parser that knows how to parse the custom type.

FallBack is thrown specifically, and it's due to the lack of custom parser in this case. Please make sure that correct api is used.

Please re-open it if this doesn't solve the issue.

Thank you.

[Aditya0603]

@nesalang I am using this method itself setBaseCardElementRenderer.

Let me rephrase the question here.
For some specific case we don't need to render the Media element, and instead render the fallback element (if provided).

So I set a new renderer for Media using setBaseCardElementRenderer.

[registration setBaseCardElementRenderer:[CustomMediaRenderer getInstance] cardElementType:ACRMedia];
and threw a exception in the render method so that the fallback elements render

- (UIView *)render:(UIView<ACRIContentHoldingView> *)viewGroup rootView:(ACRView *)rootView inputs:(NSArray *)inputs baseCardElement:(ACOBaseCardElement *)acoElem hostConfig:(ACOHostConfig *)acoConfig { @throw [ACOFallbackException fallbackException]; }

this crashed the app , instead it should have rendered the fallback elements

[jwoo-msft]

@Aditya0603 thanks for the clarification. This is due to the text preprocessing for performance. I'm going to update the issue description.