Reactive Programming in iOS with Combine

Feb 4 2021 Swift 5.3, macOS 11.0, Xcode 12.2

Part 3: Combining Operators

17. Challenge: Append and Prepend

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This video was last updated on Feb 4 2021

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You’ve learned all about Prepending and Appending operators - so now it’s time for a challenge. Back in the day, phone numbers used to be a lot easier to remember! 7 digits (in the United States, at least) was all you needed to remember to call your best friend. Now you need area codes, and if you’re calling a business, you’ll probably need to know a person’s extension, and if the number was long distance, you’d need to prepend a “1” in front of it. So for this challenge:

example(of: "Making Phone Numbers") {

  let phoneNumbersPublisher = ["123-4567"].publisher
  let areaCode = "410"
  let phoneExtension = "901"

  phoneNumbersPublisher
    .prepend("1-", areaCode, "-")
    .append(" EXT ")
    .append(phoneExtension)
    .collect()
    .sink(receiveValue:
    {
      print($0.joined())
    })
    .store(in: &subscriptions)
}