You cannot translate Java to Swift automatically . There are too many differences. To speed up an application, you have to find out which parts of the code consume most of the time, then redesign the program in such a way that it does it more efficiently.
Read moreIs it possible to use Java code in flutter?
Flutter uses a flexible system that allows you to call platform-specific APIs in a language that works directly with those APIs: Kotlin or Java on Android .
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