#03: String trimming in Swift 3

In another short post we’ve seen how to split strings in Swift, this post will show you how to trim them form surrounding spaces or other unwanted characters.

This can be done quite easily leveraging the NSString class from Foundation.

In the snippet below, we’ll remove the whitespaces an the trailing newline that surround a Shakespeare quote:


import Foundation

var aline = "  This above all: to thine own self be true        \n"
aline.trimmingCharacters(in: .whitespacesAndNewlines) //This above all: to thine own self be true

There are a few default CharacterSet provided via static property to choose from in addition to the whitespacesAndNewlines we used here.

Value	Description
.controlCharacters	Characters in Unicode General Category Cc and Cf.
.whitespaces	Characters in Unicode General Category Zs and `CHARACTER TABULATION (U+0009)`.
.whitespacesAndNewlines	Characters in Unicode General Category Z*, `U+000A ~ U+000D`, and `U+0085`.
.decimalDigits	Characters in the category of Decimal Numbers.
.letters	Characters in Unicode General Category L* & M*.
.lowercaseLetters	Characters in Unicode General Category Ll.
.uppercaseLetters	Characters in Unicode General Category Lu and Lt.
.nonBaseCharacters	Characters in Unicode General Category M*.
.alphanumerics	Characters in Unicode General Categories L, M, and N*.
.decomposables	Individual Unicode characters that can also be represented as composed character sequences (such as for letters linked with accents)
.illegalCharacters	Non-Characters or that have not yet been defined in version 3.2 of the Unicode standard.
.punctuationCharacters	Characters in Unicode General Category P*.
.capitalizedLetters	Characters in Unicode General Category Lt.
.symbols	Characters in Unicode General Category S*.
.newlines	Containing the newline characters (`U+000A ~ U+000D`, `U+0085`, `U+2028`, and `U+2029`).
.urlUserAllowed	Characters allowed in a user URL subcomponent.
.urlPasswordAllowed	Characters allowed in a password URL subcomponent.
.urlHostAllowed	Characters allowed in a host URL subcomponent.
.urlPathAllowed	Characters allowed in a path URL component.
.urlQueryAllowed	Characters allowed in a query URL component.
.urlFragmentAllowed	Characters allowed in a fragment URL component.

Additionally, custom set of characters can be created specifying all the characters you need in a string:


var myCharset= CharacterSet("#%&")
aline.trimmingCharacters(in: myCharset)

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