`Trim`

Often strings contain whitespace (like spaces or newlines) at their starts or ends. These characters are often removed or trimmed.

In Foundation, using Swift 5.8, we can access a method called trimmingCharacters. A character set is required. The result is a string with the specified characters removed.

An example

Let us begin with a simple example. We introduce a "source" string that contains a leading space, and a trailing period and space.

Start We create a CharacterSet with 3 characters—a space, period, and a question mark.

Next We invoke the trim method, trimmingCharacters. We pass the set instance as an argument.

Result The string returned has no leading or trailing spaces (and no period).

import Foundation

// The string we are trimming.
let source = " Programming in Swift. "

// Create a character set of chars to trim.
let set = CharacterSet(charactersIn: " .?")

// Call func with character set.
let result = source.trimmingCharacters(in: set)

// Write the result.
print(result)
Programming in Swift

An alternative

A custom pair of loops (for startIndex and endIndex) could be written. In these, we continue towards the center of a string as removable characters are encountered.

Then We take a substring (of the inner part of the string) to perform the trimming operation.

In Swift, strings are manipulated in many ways. With convenient methods like trimmingCharacters, we avoid writing complex logic to eliminate characters.