Kotlin Coroutine bridges: converting any callback-based Android API to suspend functions

Android platform APIs and third-party SDKs commonly rely on callbacks, which can lead to complex and hard-to-maintain code with nested callback chains. Kotlin coroutines offer a solution through suspend functions, but these are not readily available, requiring developers to implement a bridge pattern using suspendCoroutine. This approach allows callback-based APIs to be converted into cleaner, more readable suspend functions. The article explores key elements of this pattern, including handling various callback shapes, designing exception hierarchies, and employing production techniques like those in RevenueCat's SDK. It also emphasizes the importance of maintaining structured error information through typed exceptions and demonstrates the flexibility of the Result<T> variant for error handling. This bridge pattern is applicable beyond billing APIs to any callback-based Android API, offering a more sequential, testable, and composable approach to coding.