How to add a little red dot of unread messages to the app icon of mixed development?

problem description

if there is an unread message, a small red dot, or a red badge number, will be displayed on the upper-right corner of the app icon.
how to implement it in mixed development?

the environmental background of the problems and what methods you have tried

data can be obtained through websock long polling

related codes

/ / Please paste the code text below (do not replace the code with pictures)

what result do you expect? What is the error message actually seen?

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