ControlNotificationStream.prefix(_:)

Use prefix(_:) to reduce the number of elements produced by the asynchronous sequence.

In this example, an asynchronous sequence called Counter produces Int values from 1 to 10. The prefix(_:) method causes the modified sequence to pass through the first six values, then end.

for await number in Counter(howHigh: 10).prefix(6) { print(number, terminator: " ") } // Prints "1 2 3 4 5 6 "

If the count passed to prefix(_:) exceeds the number of elements in the base sequence, the result contains all of the elements in the sequence.

• Parameter count: The maximum number of elements to return. The value of count must be greater than or equal to zero.
• Returns: An asynchronous sequence starting at the beginning of the base sequence with at most count elements.