While

A while loop performs a set of statements until a condition becomes false. These kinds of loops are best used when the number of iterations isn’t known before the first iteration begins.

Swift provides two kinds of while loops:

• while evaluates its condition at the start of each pass through the loop.
• repeat-while evaluates its condition at the end of each pass through the loop.

While

A while loop starts by evaluating a single condition. If the condition is true, a set of statements is repeated until the condition becomes false.

var square = 0
var diceRoll = 0
while square < 25 {
    // Roll the dice
    diceRoll += 1
    if diceRoll == 7 { diceRoll = 1 }
    // Move
    square += diceRoll
}
print("Game over!")

Repeat-While

The other variation of the while loop, known as the repeat-while loop, performs a single pass through the loop block first, before considering the loop’s condition. It then continues to repeat the loop until the condition is false.

var i = 0
repeat {
    print(i)
    i += 1
} while i < 5
// Prints 0, 1, 2, 3, 4