Swift - Repeat While loop

In Swift, the repeat-while loop, formerly known as do-while in some other languages, is a control flow structure that first executes a block of code and then evaluates a condition to decide whether to repeat the block again.

Here's the basic syntax:

repeat {
    // code to execute
} while condition

The loop executes the code inside the repeat block and then checks the condition specified in the while clause. If the condition is true, the loop will execute the code in the repeat block again. This will continue until the condition becomes false.

One notable feature of the repeat-while loop is that the code inside the loop will always execute at least once, even if the condition is false to start with, because the condition check happens after the code block is executed.

Here's a simple example:

var counter = 0

repeat {
    print("Counter is \(counter)")
    counter += 1
} while counter < 3

// Output:
// Counter is 0
// Counter is 1
// Counter is 2

In this example, the code block inside the repeat-while loop will execute until counter is no longer less than 3.

To decide between using a repeat-while loop or a regular while loop, consider whether you want the loop's code block to execute at least once regardless of the initial condition (repeat-while) or if you want the condition checked before any execution of the loop's code (while).

How to use repeat-while loop in Swift:
Description: The repeat-while loop in Swift repeats a block of code while a condition is true.
```
var count = 0

repeat {
    print("Count: \(count)")
    count += 1
} while count < 5
```

Comparing repeat-while vs while loop in Swift:

Description: The key difference is that repeat-while guarantees at least one execution, while while checks the condition before the first execution.

var num = 5

// Using repeat-while
repeat {
    print("Repeat-while: \(num)")
    num -= 1
} while num > 0

// Using while
var num2 = 5
while num2 > 0 {
    print("While: \(num2)")
    num2 -= 1
}

Exiting repeat-while loop with break in Swift:
Description: You can use the break statement to exit a repeat-while loop prematurely.
```
var counter = 0

repeat {
    print(counter)
    counter += 1
    if counter == 3 {
        break
    }
} while true
```

Nested repeat-while loops in Swift:

Description: You can nest repeat-while loops to create more complex iteration patterns.

var i = 1

repeat {
    var j = 1
    repeat {
        print("(\(i), \(j))")
        j += 1
    } while j <= 3
    i += 1
} while i <= 3

Using continue statement in repeat-while loop:
Description: The continue statement allows you to skip the rest of the code inside the loop for the current iteration.
```
var num = 0

repeat {
    num += 1
    if num % 2 == 0 {
        continue
    }
    print(num)
} while num < 5
```

Conditional statements with repeat-while in Swift:

Description: You can use conditional statements inside a repeat-while loop to control its flow.

var number = 0

repeat {
    if number % 2 == 0 {
        print("Even")
    } else {
        print("Odd")
    }
    number += 1
} while number < 3

Swift repeat-while loop vs for loop:
Description: repeat-while and for loops are different constructs. repeat-while checks the condition after each iteration, while a for loop iterates over a sequence.
```
// Using repeat-while
var i = 0
repeat {
    print("Repeat-while: \(i)")
    i += 1
} while i < 3

// Using for loop
for j in 0..<3 {
    print("For loop: \(j)")
}
```