If - Else

Sometimes you need your program to do one thing when a condition is true and something different when it's false. The else clause provides an alternative path of execution.

let temperature = 15

if temperature > 25 {
    print("It's warm outside")
} else {
    print("It's cool outside")
}

When the condition is false, the code inside the else block runs instead. This guarantees that exactly one of the two code blocks will always execute.

For situations with more than two possibilities, you can chain multiple conditions using else if:

let score = 75

if score >= 90 {
    print("Excellent")
} else if score >= 70 {
    print("Good")
} else if score >= 50 {
    print("Pass")
} else {
    print("Fail")
}

Swift evaluates each condition from top to bottom and executes the first block where the condition is true. The final else acts as a catch-all for any remaining cases. This structure lets you handle multiple distinct scenarios in a clear, readable way.