Swift 3 ObjectOriented Programming - Second Edition

Using map to transform values

The map method takes a closure as an argument, calls it for each item in the array, and returns a mapped value for the item. The returned mapped value can be of a different type from the item's type.

The following lines declare a new getUppercasedNames method for our previously coded GameRepository class that performs the simplest map operation. The code file for the sample is included in the swift_3_oop_chapter_07_21 folder:

    open func getUppercasedNames() -> [String] { 
      return getAll().map({ game in game.name.uppercased() }) 
    } 

The getUppercasedGames parameterless method returns Array<String>, specified with the [String] shortcut. The code calls the getAll method and calls the map method for the result with a closure ...