The switch statement in Objective-C is used to evaluate an expression and perform different actions based on the value of the expression. The syntax of the switch statement is as follows:
switch(expression) {
case constant1:
// code to execute if expression is equal to constant1
break;
case constant2:
// code to execute if expression is equal to constant2
break;
default:
// code to execute if expression doesn't match any constants
break;
}
The expression is usually a variable or a value that we want to compare against a set of constant values. The case statements specify the possible values that the expression may have and the code to execute if the expression matches that value. The break statement is used to terminate the case and exit the switch statement. The default statement is optional and specifies the code to execute if the expression doesn't match any of the specified constants.
Here is an example of a switch statement that evaluates the value of a variable grade and performs different actions based on the value:
NSString *grade = @"B";
switch(grade) {
case @"A":
NSLog(@"Excellent!");
break;
case @"B":
NSLog(@"Good!");
break;
case @"C":
NSLog(@"Fair!");
break;
case @"D":
NSLog(@"Needs Improvement!");
break;
default:
NSLog(@"Invalid Grade!");
break;
}
In this example, if the variable grade has a value of "B", the switch statement will execute the code under the second case statement, which is to print "Good!" to the console. If the variable grade has a value of "X", which doesn't match any constants in the case statements, the switch statement will execute the code under the default statement, which is to print "Invalid Grade!".