How do I bridge delegate callbacks to AsyncStream in Swift?

In Swift, you can bridge delegate callbacks to an `AsyncStream` to allow asynchronous handling of delegate methods. This can be particularly useful when dealing with UI updates or networking callbacks that follow a delegate pattern. Below is an example of how to implement this bridging.


    import Foundation

    // Define a delegate protocol
    protocol SomeDelegate: AnyObject {
        func didReceiveData(_ data: Data)
    }

    // A class that follows the delegate pattern
    class DataSource {
        weak var delegate: SomeDelegate?

        func fetchData() {
            // Simulate an async operation
            DispatchQueue.global().async {
                // Simulate data received
                let data = "Hello, World!".data(using: .utf8)!
                
                // Notify the delegate on the main thread
                DispatchQueue.main.async {
                    self.delegate?.didReceiveData(data)
                }
            }
        }
    }

    // Bridging to AsyncStream
    struct AsyncDataSource {
        var dataSource: DataSource

        func stream() -> AsyncStream {
            AsyncStream { continuation in
                dataSource.delegate = DelegateAdapter(continuation: continuation)
                dataSource.fetchData()
            }
        }
    }

    final class DelegateAdapter: SomeDelegate {
        let continuation: AsyncStream.Continuation

        init(continuation: AsyncStream.Continuation) {
            self.continuation = continuation
        }

        func didReceiveData(_ data: Data) {
            continuation.yield(data)
            continuation.finish()  // Complete the stream if needed
        }
    }

    // Usage example
    let dataSource = DataSource()
    let asyncDataSource = AsyncDataSource(dataSource: dataSource)

    Task {
        for await data in asyncDataSource.stream() {
            if let message = String(data: data, encoding: .utf8) {
                print(message)  // Output: Hello, World!
            }
        }
    }

How do I bridge delegate callbacks to AsyncStream in Swift?

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How do I bridge delegate callbacks to AsyncStream in Swift?

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