The logical, &&, operator evaluates two operands and returns a Boolean result. It returns true only when both operands are true and returns false when at least one operand is false.

&& is denoted by two ampersand symbols and translates to AND.

The following truth table demonstrates all of the possible outcomes of an expression using &&.

Let’s see the && operator in action. Assume we’re writing a program for an application that dims a screen by 25% in the evening time. We can set up the following if/else statement for this case:

var time = 8 // PM 
var phoneInUse = true 
var brightness: Double

if time >= 8 && phoneInUse {
  brightness = 0.75 
} else {
  brightness = 1 
}

print(brightness) // Prints: 0.75

Notice how the brightness will be set to 75% only when time >= 8 and phoneInUse are both true. Changing the value of time to be less than 8 or setting phoneInUse to false, would result in the brightness remaining the same.