String to Int in Swift

In Swift, you can convert a string to an integer using the Int() initializer. Here are a few examples:

Example 1: Convert a string with a numeric value to an integer.

let str = "123"
let num = Int(str)
print(num)

Optional(123)

The Int() initializer returns an optional Int value because the conversion can fail if the string does not contain a valid numeric value. In this case, the conversion is successful and the output is Optional(123).

Example 2: Convert a string with a non-numeric value to an integer.

let str = "abc"
let num = Int(str)
print(num)

nil

The Int() initializer returns nil if the string does not contain a valid numeric value. In this case, the output is nil.

Example 3: Convert a string with a numeric value and handle the optional output.

let str = "456"
if let num = Int(str) {
    print(num)
} else {
    print("Invalid number")
}

456

The if let statement is used to safely unwrap the optional Int value returned by the Int() initializer. If the conversion is successful, the unwrapped value is printed to the console. If the conversion fails, the else block is executed and prints "Invalid number".

Note that the Int() initializer can also be used to convert a string with a hexadecimal value to an integer by passing in a second argument of radix: 16. For example:

let str = "A"
let num = Int(str, radix: 16)
print(num)

Optional(10)