Async sequences in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an async sequence using AsyncStream.

iOS Swift

let numbers = AsyncStream<Int> { continuation in
    continuation.yield(1)
    continuation.yield(2)
    continuation.finish()
}

Task: Use a for await loop to iterate over [1].

Drag options to blanks, or click blank then click option'

Anumbers

BArray

CDispatchQueue

DTask

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to iterate over Array with for await (Array is not async sequence).

Using DispatchQueue or Task instead of the async sequence variable.

The variable numbers is the async sequence created with AsyncStream. You use for await to iterate over it.

2fill in blank

medium

Complete the async function to return an AsyncStream of integers from 1 to 3.

iOS Swift

func makeNumbers() -> AsyncStream<Int> {
    AsyncStream { continuation in
        for i in 1...3 {
            continuation.[1](i)
        }
        continuation.finish()
    }
}

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Asend

Byield

Cemit

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Using send, emit, or push which are not valid methods for AsyncStream.

The method to send values to an AsyncStream is yield.

3fill in blank

hard

Fix the error in the async sequence iteration by completing the missing keyword.

iOS Swift

func printNumbers() async {
    let stream = AsyncStream<Int> { continuation in
        continuation.yield(10)
        continuation.finish()
    }

    for [1] number in stream {
        print(number)
    }
}

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Alet

Basync

Cawait

Dyield

Attempts:

3 left

💡 Hint

Common Mistakes

Using for async or just for which causes errors.

When iterating over an async sequence, you must use for await to wait for each value asynchronously.

4fill in blank

hard

Fill both blanks to create an AsyncStream that yields strings and finishes properly.

iOS Swift

let greetings = AsyncStream<String> { [1] in
    [2].yield("Hello")
    [2].finish()
}

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Acontinuation

Bstream

Ctask

Dsequence

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the parameter and calls causing errors.

The closure parameter is usually named continuation. You call yield and finish on it.

5fill in blank

hard

Fill all three blanks to create a filtered async sequence of integers greater than 5.

iOS Swift

let filtered = AsyncStream<Int> { continuation in
    for i in 1...10 {
        if i [1] 5 {
            continuation.[2](i)
        }
    }
    continuation.[3]()
}

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A>

Byield

Cfinish

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using < or wrong method names causing logic or syntax errors.

The condition checks if i > 5. Then yield sends the value, and finish ends the stream.