Programming in Swift: Functions & Types

Jan 4 2022 · Swift 5.5, iOS 15, Xcode 13

Part 2: Closures

15. compactMap & flatMap

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Notes: 15. compactMap & flatMap

Update Notes: This course was originally recorded in 2019. It has been reviewed and all content and materials updated as of October 2021.

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There are two more handy methods with map in the name: compactMap and flatMap. Both of them return an array, like map, but they also do a little more work for you behind the scenes.

var arrayForValidInput: [Int] = []

for input in userInput {

}

  guard let input = Int(input) else {
    continue
  }

  arrayForValidInput.append(input)
} 
arrayForValidInput 

let validInput = userInput.compactMap { input in
  
}

let validInput = userInput.compactMap { 
  
}

let validInput = userInput.compactMap { 😺input in🛑
  
}

Int(input)

let dwarvesAfterM = 

let dwarvesAfterM = arrayOfDwarfArrays.flatMap { 
  
}

let dwarvesAfterM = arrayOfDwarfArrays.flatMap { 😺dwarves 
  
}

let dwarvesAfterM = arrayOfDwarfArrays.flatMap { dwarves 😺-> [String] in
  
}

dwarves

  var afterM: [String] = []

for dwarf in dwarves where dwarf > "M" {

}

    afterM.append(dwarf)

return afterM

var afterM: [String] = []
  for dwarf in dwarves where dwarf > "M" {
    afterM.append(dwarf)
  }
  return afterM