Cocoa Programming for OS X: The Big Nerd Ranch Guide

Loops and String Interpolation

Swift has all the familiar control flow statements: if-else, which you saw above, while, for, for-in, do-while, and switch. While they are familiar, there may be some differences from what you are accustomed to. The key differences with C-like languages is that while enclosing parentheses are not necessary on these statements’ expressions, braces on clauses are necessary. Additionally, the expressions for if and while-like statements must evaluate to a Bool.

Consider this very traditional C-style loop, written in Swift:

for var i = 0; i < countingUp.count; i++ {
    let string = countingUp[i]
    // Use 'string'.
}

You could do the same thing a little more cleanly using Swift’s Range type and the for ...