What is the switch statement in Swift?

In Swift, the switch statement tests a variable against several values for equality. It uses cases to test multiple conditions and execute code blocks based on the true condition.

Syntax

The basic structure of the switch statement is given below:

switch expression {
case val1:
    // Code to execute when expression matches val1
case val2:
    // Code to execute when expression matches val2
default:
    // Code to execute when none of the cases match
}
Basic syntax of switch statement

In the code above, the switch keyword is used, followed by expression to be evaluated.

  • case: Inside the switch statement, there are different cases to check for conditions.

  • default: It is a special type of case and is executed when none of the cases matches.

Flowchart

The following diagram illustrates the flow of control in a switch statement:

Working of switch statement
Working of switch statement

Code example 1

A switch statement can be used to match against a specific value of an expression.

let choice = 2
switch choice {
case 1:
    print("Eat")
case 2:
    print("Sleep")
case 3: 
    print("Play games")
default:
    print("Take a rest")
}

Code explanation

  • Line 1: We define and declare the choice variable.

  • Line 3: The choice variable is passed to the switch statement, and its value is evaluated.

  • Line 4: If the expression value is equal to 1, the code inside case 1 will get executed.

  • Line 6: If the expression value is equal to 2, the code inside case 2 will get executed.

  • Line 8: If the expression value is equal to 3, the code inside case 3 will get executed.

  • Line 11: If none of the cases match, the code inside default will get executed.

Code example 2

A switch statement can also be used to match against a range of values of an expression.

let score = 67
switch score {
case 0..<50:
    print("Failed")
case 50..<70:
    print("Pass")
case 70..<85:
    print("Good")
default:
    print("Excellent")
}

Code explanation

  • Line 4: If the expression value is greater or equal to 0 and less than 50, the code inside case 0..<50 will get executed.

  • Line 6: If the expression value is greater or equal to 50 and less than 70, the code inside case 50..<70 will get executed.

  • Line 8: If the expression value is greater or equal to 70 and less than 85, the code inside case 70..<85 will get executed.

  • Line 10: If none of the cases match, the code inside default will get executed.

Conclusion

In conclusion, the switch statement in Swift is helpful when we have multiple conditions, and based on those conditions, we have to evaluate the code block. It can also be used to execute code blocks based on different ranges of values.

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