27. Swift uses string interpolation to include the name of a
constant or variable as a placeholder in a longer string, and
to prompt Swift to replace it with the current value of that
constant or variable. Wrap the name in parentheses and
escape it with a backslash before the opening parenthesis:
The Swift Programming Language
println("The current value of
friendlyWelcome is (friendlyWelcome)")
28. ▶ 文字列の中に値を埋め込む仕組み
▶ (value) という書式で埋め込む
// value の値は "Swift 2.1" になる
let version = 2.1
let value = "Swift (version)"
要点
String Interpolation