Swift While Loop
Execute code repeatedly while conditions are true
⏳ What is While Loop?
Swift while loops execute code repeatedly as long as a condition remains true. They're perfect for situations where you don't know the exact number of iterations needed beforehand.
// Basic while loop
var count = 1
while count <= 3 {
print("Count: \(count)")
count += 1
}
Output:
Count: 1
Count: 2
Count: 3
While Loop Characteristics
Condition First
Checks condition before execution
while condition {
// May not execute at all
}Unknown Iterations
Perfect for uncertain loop counts
while !found {
// Keep searching
}Infinite Risk
Can run forever if condition never changes
while true {
// Dangerous!
break // Need exit
}Variable Control
Loop variable must be managed manually
var i = 0
while i < 10 {
i += 1 // Don't forget!
}🔹 Basic While Loop Syntax
The condition is evaluated before each iteration:
var number = 10
while number > 0 {
print("Countdown: \(number)")
number -= 1
}
print("Launch! 🚀")
// Example with boolean condition
var gameRunning = true
var lives = 3
while gameRunning && lives > 0 {
print("Playing game... Lives: \(lives)")
lives -= 1
if lives == 0 {
gameRunning = false
}
}Output:
Countdown: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
Launch! 🚀
Playing game... Lives: 3
Playing game... Lives: 2
Playing game... Lives: 1
🔹 While vs For-In Comparison
Choose the right loop for your situation:
// For-in: Known number of iterations
for i in 1...5 {
print("For-in: \(i)")
}
// While: Unknown number of iterations
var attempts = 0
var success = false
while !success && attempts < 5 {
attempts += 1
print("Attempt \(attempts)")
// Simulate random success
success = attempts == 3 // Success on 3rd attempt
}
if success {
print("Success after \(attempts) attempts!")
} else {
print("Failed after \(attempts) attempts")
}Output:
For-in: 1, 2, 3, 4, 5
Attempt 1
Attempt 2
Attempt 3
Success after 3 attempts!
🔹 Common While Loop Patterns
Typical use cases for while loops:
// Pattern 1: Input validation
var userInput = ""
while userInput.isEmpty {
print("Please enter your name:")
userInput = "John" // Simulated input
}
// Pattern 2: Processing until empty
var tasks = ["Task 1", "Task 2", "Task 3"]
while !tasks.isEmpty {
let task = tasks.removeFirst()
print("Completed: \(task)")
}
// Pattern 3: Search with condition
let numbers = [2, 4, 7, 8, 10]
var index = 0
var found = false
while index < numbers.count && !found {
if numbers[index] % 2 == 1 { // Looking for odd number
print("Found odd number: \(numbers[index]) at index \(index)")
found = true
}
index += 1
}Output:
Please enter your name:
Completed: Task 1
Completed: Task 2
Completed: Task 3
Found odd number: 7 at index 2