Looping with while loops

for loops are great when you know how many times you intend to loop, but if you want to loop until a certain condition is met, you need a while loop.

A while loop has the following syntax:

while <#boolean expression#> { 
    <#code to execute#> 
} 

The code block will execute over and over until the Boolean expression returns false. Therefore, it's a common pattern to change some value in the code block that may cause the Boolean expression to change to false.

In this recipe, we will look at situations where a while loop can be useful for repeating actions.

Getting ready

This recipe will involve simulating the random flip of a coin. To flip our coin, we will need to randomly pick either heads or tails, so we will need to use a random number generator from the Foundation framework. We will discuss Foundation further in Chapter 5...