Until now, we’ve been working with conditionals that can handle only one condition. If that condition is met, our program follows one course of action, otherwise it follows another.

Swift provides us with a tool called the else if statement which allows us to add additional conditions to a standard if/else statement.

Here’s how it works:

if condition1 {
  this code runs when condition1 is true 
} else if condition2 {
  this code runs when condition2 is true 
} else if condition3 {
  this code runs when condition3 is true 
} else {
  this code runs when all previous conditions are false 
}

• Similarly to an if statement, an else if statement accepts a condition and a code block to execute for when that condition is true.

• The else if statement exists only between an if and an else and cannot stand on its own like the if statement can.

• Any number of else if statements can exist between an if and an else.

Working off the previous example, assume we’d like to update the grading scale in a school to use the academic grading scale used in the U.S..

We can translate numerical grades to letter grades, "A", "B", "C", etc. with the help of multiple else if statements:

let grade = 85
let letterGrade: String 

if grade >= 90 {
  letterGrade = "A"
} else if grade >= 80 {
  letterGrade = "B"
} else if grade >= 70 {
  letterGrade = "C"
} else if grade >= 60 {
  letterGrade = "D"
} else if grade < 60 {
  letterGrade = "F"
} else {
  letterGrade = "N/A"
}

print(letterGrade) 
// Prints: B

Since a student’s numerical grade is 85, the first else if statement executes, and the value of letterGrade becomes "B".