Remove last character from string. Swift language

Question

How can I remove last character from String variable using Swift? Can't find it in documentation.

Here is full example:

var expression = "45+22"
expression = expression.substringToIndex(countElements(expression) - 1)

Answer 1

Swift 4.0 (also Swift 5.0)

var str = "Hello, World"                           // "Hello, World"
str.dropLast()                                     // "Hello, Worl" (non-modifying)
str                                                // "Hello, World"
String(str.dropLast())                             // "Hello, Worl"

str.remove(at: str.index(before: str.endIndex))    // "d"
str                                                // "Hello, Worl" (modifying)

Swift 3.0

The APIs have gotten a bit more swifty, and as a result the Foundation extension has changed a bit:

var name: String = "Dolphin"
var truncated = name.substring(to: name.index(before: name.endIndex))
print(name)      // "Dolphin"
print(truncated) // "Dolphi"

Or the in-place version:

var name: String = "Dolphin"
name.remove(at: name.index(before: name.endIndex))
print(name)      // "Dolphi"

Thanks Zmey, Rob Allen!

Swift 2.0+ Way

There are a few ways to accomplish this:

Via the Foundation extension, despite not being part of the Swift library:

var name: String = "Dolphin"
var truncated = name.substringToIndex(name.endIndex.predecessor())
print(name)      // "Dolphin"
print(truncated) // "Dolphi"

Using the removeRange() method (which alters the name):

var name: String = "Dolphin"    
name.removeAtIndex(name.endIndex.predecessor())
print(name) // "Dolphi"

Using the dropLast() function:

var name: String = "Dolphin"
var truncated = String(name.characters.dropLast())
print(name)      // "Dolphin"
print(truncated) // "Dolphi"

Old String.Index (Xcode 6 Beta 4 +) Way

Since String types in Swift aim to provide excellent UTF-8 support, you can no longer access character indexes/ranges/substrings using Int types. Instead, you use String.Index:

let name: String = "Dolphin"
let stringLength = count(name) // Since swift1.2 `countElements` became `count`
let substringIndex = stringLength - 1
name.substringToIndex(advance(name.startIndex, substringIndex)) // "Dolphi"

Alternatively (for a more practical, but less educational example) you can use endIndex:

let name: String = "Dolphin"
name.substringToIndex(name.endIndex.predecessor()) // "Dolphi"

Note: I found this to be a great starting point for understanding String.Index

Old (pre-Beta 4) Way

You can simply use the substringToIndex() function, providing it one less than the length of the String:

let name: String = "Dolphin"
name.substringToIndex(countElements(name) - 1) // "Dolphi"

Answer 2

The global dropLast() function works on sequences and therefore on Strings:

var expression  = "45+22"
expression = dropLast(expression)  // "45+2"

// in Swift 2.0 (according to cromanelli's comment below)
expression = String(expression.characters.dropLast())

Answer 3

Swift 4:

let choppedString = String(theString.dropLast())

In Swift 2, do this:

let choppedString = String(theString.characters.dropLast())

I recommend this link to get an understanding of Swift strings.

Answer 4

Swift 4/5

var str = "bla"
str.removeLast() // returns "a"; str is now "bl"

Answer 5

This is a String Extension Form:

extension String {

    func removeCharsFromEnd(count_:Int) -> String {
        let stringLength = count(self)

        let substringIndex = (stringLength < count_) ? 0 : stringLength - count_

        return self.substringToIndex(advance(self.startIndex, substringIndex))
    }
}

for versions of Swift earlier than 1.2:

...
let stringLength = countElements(self)
...

---

Usage:

var str_1 = "Maxim"
println("output: \(str_1.removeCharsFromEnd(1))") // "Maxi"
println("output: \(str_1.removeCharsFromEnd(3))") // "Ma"
println("output: \(str_1.removeCharsFromEnd(8))") // ""

---

Reference:

Extensions add new functionality to an existing class, structure, or enumeration type. This includes the ability to extend types for which you do not have access to the original source code (known as retroactive modeling). Extensions are similar to categories in Objective-C. (Unlike Objective-C categories, Swift extensions do not have names.)

See DOCS

Answer 6

Use the function removeAtIndex(i: String.Index) -> Character:

var s = "abc"    
s.removeAtIndex(s.endIndex.predecessor())  // "ab"

Answer 7

Swift 4

var welcome = "Hello World!"
welcome = String(welcome[..<welcome.index(before:welcome.endIndex)])

or

welcome.remove(at: welcome.index(before: welcome.endIndex))

or

welcome = String(welcome.dropLast())

Answer 8

The easiest way to trim the last character of the string is:

title = title[title.startIndex ..< title.endIndex.advancedBy(-1)]

Answer 9

import UIKit

var str1 = "Hello, playground"
str1.removeLast()
print(str1)

var str2 = "Hello, playground"
str2.removeLast(3)
print(str2)

var str3 = "Hello, playground"
str3.removeFirst(2)
print(str3)

Output:-
Hello, playgroun
Hello, playgro
llo, playground

Answer 10

let str = "abc"
let substr = str.substringToIndex(str.endIndex.predecessor())  // "ab"

Answer 11

var str = "Hello, playground"

extension String {
    var stringByDeletingLastCharacter: String {
        return dropLast(self)
    }
}

println(str.stringByDeletingLastCharacter)   // "Hello, playgroun"

Answer 12

Short answer (valid as of 2015-04-16): removeAtIndex(myString.endIndex.predecessor())

Example:

var howToBeHappy = "Practice compassion, attention and gratitude. And smile!!"
howToBeHappy.removeAtIndex(howToBeHappy.endIndex.predecessor())
println(howToBeHappy)
// "Practice compassion, attention and gratitude. And smile!"

Meta:

The language continues its rapid evolution, making the half-life for many formerly-good S.O. answers dangerously brief. It's always best to learn the language and refer to real documentation.

Answer 13

With the new Substring type usage:

Swift 4:

var before: String = "Hello world!"
var lastCharIndex: Int = before.endIndex
var after:String = String(before[..<lastCharIndex])
print(after) // Hello world

Shorter way:

var before: String = "Hello world!"
after = String(before[..<before.endIndex])
print(after) // Hello world

Answer 14

Use the function advance(startIndex, endIndex):

var str = "45+22"
str = str.substringToIndex(advance(str.startIndex, countElements(str) - 1))

Answer 15

A swift category that's mutating:

extension String {
    mutating func removeCharsFromEnd(removeCount:Int)
    {
        let stringLength = count(self)
        let substringIndex = max(0, stringLength - removeCount)
        self = self.substringToIndex(advance(self.startIndex, substringIndex))
    }
}

Use:

var myString = "abcd"
myString.removeCharsFromEnd(2)
println(myString) // "ab"

Answer 16

Another way If you want to remove one or more than one character from the end.

var myStr = "Hello World!"
myStr = (myStr as NSString).substringToIndex((myStr as NSString).length-XX)

Where XX is the number of characters you want to remove.

Answer 17

Swift 3 (according to the docs) 20th Nov 2016

let range = expression.index(expression.endIndex, offsetBy: -numberOfCharactersToRemove)..<expression.endIndex
expression.removeSubrange(range)

Answer 18

The dropLast() function removes the last element of the string.

var expression = "45+22"
expression = expression.dropLast()

Answer 19

Swift 4.2

I also delete my last character from String (i.e. UILabel text) in IOS app

@IBOutlet weak var labelText: UILabel! // Do Connection with UILabel

@IBAction func whenXButtonPress(_ sender: UIButton) { // Do Connection With X Button

    labelText.text = String((labelText.text?.dropLast())!) // Delete the last caracter and assign it

}

Answer 20

I'd recommend using NSString for strings that you want to manipulate. Actually come to think of it as a developer I've never run into a problem with NSString that Swift String would solve... I understand the subtleties. But I've yet to have an actual need for them.

var foo = someSwiftString as NSString

or

var foo = "Foo" as NSString

or

var foo: NSString = "blah"

And then the whole world of simple NSString string operations is open to you.

As answer to the question

// check bounds before you do this, e.g. foo.length > 0
// Note shortFoo is of type NSString
var shortFoo = foo.substringToIndex(foo.length-1)

Answer 21

complimentary to the above code I wanted to remove the beginning of the string and could not find a reference anywhere. Here is how I did it:

var mac = peripheral.identifier.description
let range = mac.startIndex..<mac.endIndex.advancedBy(-50)
mac.removeRange(range)  // trim 17 characters from the beginning
let txPower = peripheral.advertisements.txPower?.description

This trims 17 characters from the beginning of the string (he total string length is 67 we advance -50 from the end and there you have it.

Answer 22

Swift 3: When you want to remove trailing string:

func replaceSuffix(_ suffix: String, replacement: String) -> String {
    if hasSuffix(suffix) {
        let sufsize = suffix.count < count ? -suffix.count : 0
        let toIndex = index(endIndex, offsetBy: sufsize)
        return substring(to: toIndex) + replacement
    }
    else
    {
        return self
    }
}

Answer 23

I prefer the below implementation because I don't have to worry even if the string is empty

let str = "abc"
str.popLast()

// Prints ab

str = ""
str.popLast() // It returns the Character? which is an optional

// Print <emptystring>