Swift Expressions, Statements and Code Blocks

An expression is a combination of variables, operators, literals, and functions. For example,

// assign value to marks
var marks = 80

// compare num1 and num2
var result = (num1 == num2)

Here, expressions are:

var marks = 80 - represents we are assigning 80 to marks
num1 == num2 - compares num1 and num2

Statements are instructions to perform a specific task. For example,

print("Hello World")

Here, we have used the print statement to instruct the computer to display the text "Hello World".

There are three types of statements in Swift:

The simple statement consists of either an expression or declaration. For example,

Here, var score = 9 * 5 is a statement that assigns the result of 9 * 5 to the score variable.

Simple statements are the most common types of statements in Swift. The print statement we have used earlier is also an example of simple statements.

The conditional statement allows us to execute a certain block of code only when certain conditions are met. For example,

var age = 25
if (age > 18) {
print("Can Vote")
}

In the above example, if (age > 18) is a conditional statement. Here, the print statement is only executed if the condition age > 18 is true.

Loop statements allow us to repeatedly execute a block of code. For example,

// create a loop statement
for i in 1...3 {
print("Hello, World!")
}

Output

Hello, World!
Hello, World!
Hello, World!

In the above example, we have used a for loop statement: for i in 1...3. It executes the print statement 3 times.

There are three types of looping statements in Swift.

A code block is a group of statements (zero or more) that is enclosed in curly braces { }. For example,

if true { // start of block
let sum = 2+3
print("Result is \(sum)")
} // end of block

Here, the code block consists two statements:

let sum = 2+3
print("Result is \(sum)")