Hi Hamdi Boyaci,
At present we do not have support for opening an attachment on PDF files in Flutter SfPdfViewer. We do not have any immediate plans to implement this feature. At the planning stage for every release cycle, we review all open features and identify features for implementation based on specific parameters including product vision, technological feasibility, and customer interest. We will let you know when this feature is implemented. The status of the feature can be tracked by the following link,
https://www.syncfusion.com/feedback/36676/attachments
Regards,
Deepika Ravi.
