How do I concatenate strings in Swift?

You can add a string in these ways:

• str += ""
• str = str + ""
• str = str + str2
• str = "" + ""
• str = "\(variable)"
• str = str + "\(variable)"

I think I named them all.

var language = "Swift" var resultStr = "\(language) is a new programming language" 

This will work too:

var string = "swift" var resultStr = string + " is a new Programming Language" 

\ this is being used to append one string to another string.

var first = "Hi" var combineStr = "\(first) Start develop app for swift" 

You can try this also:- + keyword.

 var first = "Hi" var combineStr = "+(first) Start develop app for swift" 

Try this code.

let the_string = "Swift" let resultString = "\(the_string) is a new Programming Language" 

Very Simple:

let StringA = "Hello" let StringB = "World" let ResultString = "\(StringA)\(StringB)" println("Concatenated result = \(ResultString)") 

You can now use stringByAppendingString in Swift.

var string = "Swift" var resultString = string.stringByAppendingString(" is new Programming Language") 

Swift 5

You can achieve it using appending API. This returns a new string made by appending a given string to the receiver.

API Details : here

Use:

var text = "Hello" text = text.appending(" Namaste") 

Result:

Hello Hello Namaste 

Xcode didn't accept optional strings added with a normal string. I wrote this extensions to solve that problem:

extension String { mutating func addString(str: String) { self = self + str } } 

Then you can call it like:

var str1: String? var str1 = "hi" var str2 = " my name is" str1.addString(str2) println(str1) //hi my name is 

However you could now also do something like this:

var str1: String? var str1 = "hi" var str2 = " my name is" str1! += str2 

It is called as String Interpolation. It is way of creating NEW string with CONSTANTS, VARIABLE, LITERALS and EXPRESSIONS. for examples:

 let price = 3 let staringValue = "The price of \(price) mangoes is equal to \(price*price) " 

also

let string1 = "anil" let string2 = "gupta" let fullName = string1 + string2 // fullName is equal to "anilgupta" or let fullName = "\(string1)\(string2)" // fullName is equal to "anilgupta" 

it also mean as concatenating string values.

Hope this helps you.

I just switched from Objective-C to Swift (4), and I find that I often use:

let allWords = String(format:"%@ %@ %@",message.body!, message.subject!, message.senderName!) 

Concatenation refers to the combining of Strings in Swift. Strings may contain texts, integers, or even emojis! There are many ways to String Concatenation. Let me enumerate some:

Same String

Using +=

This is useful if we want to add to an already existing String. For this to work, our String should be mutable or can be modified, thus declaring it as a Variable. For instance:

var myClassmates = "John, Jane" myClassmates += ", Mark" // add a new Classmate // Result: "John, Jane, Mark" 

Different Strings

If we want to combine different Strings together, for instance:

let oldClassmates = "John, Jane" let newClassmate = "Mark" 

We can use any of the following:

1) Using +

let myClassmates = oldClassmates + ", " + newClassmate // Result: "John, Jane, Mark" 

Notice that the each String may be a Variable or a Constant. Declare it as a Constant if you're only gonna change the value once.

2) String Interpolation

let myClassmates = "\(oldClassmates), \(newClassmate)" // Result: "John, Jane, Mark" 

3) Appending

let myClassmates = oldClassmates.appending(newClassmate) // Result: "John, Jane, Mark" 

Refer to Strings & Characters from the Swift Book for more.

Update: Tested on Swift 5.1

To print the combined string using

Println("\(string1)\(string2)") 

or String3 stores the output of combination of 2 strings

let strin3 = "\(string1)\(string2)" 

One can also use stringByAppendingFormat in Swift.

var finalString : NSString = NSString(string: "Hello") finalString = finalString.stringByAppendingFormat("%@", " World") print(finalString) //Output:- Hello World finalString = finalString.stringByAppendingFormat("%@", " Of People") print(finalString) //Output:- Hello World Of People 

Swift 5:

Array of strings into a Single string

let array = ["Ramana","Meharshi","Awareness","Oneness","Enlightnment","Nothing"] let joined = array.joined(separator: ",") 

Swift 4.2

You can also use an extension:

extension Array where Element == String? { func compactConcate(separator: String) -> String { return self.compactMap { if let unwrappedString = $0, unwrappedString.isEmpty { return nil } else { return $0 } } .joined(separator: separator) } } 

Use:

label.text = [m.firstName, m.lastName].compactConcate(separator: " ") 

Result:

"The Man" "The" "Man" 

From: Matt Neuburg Book “iOS 13 Programming Fundamentals with Swift.” :

To combine (concatenate) two strings, the simplest approach is to use the + operator:

let s = "hello" let s2 = " world" let greeting = s + s2 

This convenient notation is possible because the + operator is overloaded: it does one thing when the operands are numbers (numeric addition) and another when the operands are strings (concatenation). The + operator comes with a += assignment shortcut; naturally, the variable on the left side must have been declared with var:

var s = "hello" let s2 = " world" s += s2 

As an alternative to +=, you can call the append(_:) instance method:

var s = "hello" let s2 = " world" s.append(s2) 

Another way of concatenating strings is with the joined(separator:) method. You start with an array of strings to be concatenated, and hand it the string that is to be inserted between all of them:

let s = "hello" let s2 = "world" let space = " " let greeting = [s,s2].joined(separator:space) 

Swift concatenate strings

Several words about performance

UI Testing Bundle on iPhone 7(real device), iOS 14, -Onone(debug, without optimizations)^[About]

var result = "" for i in 0...count { <concat_operation> } 

Count = 5_000

//Append result.append(String(i)) //0.007s 39.322kB //Plus Equal result += String(i) //0.006s 19.661kB //Plus result = result + String(i) //0.130s 36.045kB //Interpolation result = "\(result)\(i)" //0.164s 16.384kB //NSString result = NSString(format: "%@%i", result, i) //0.354s 108.142kB //NSMutableString result.append(String(i)) //0.008s 19.661kB 

Disable next tests:

• Plus up to 100_000 ~10s
• interpolation up to 100_000 ~10s
• NSString up to 10_000 -> memory issues

Count = 1_000_000

//Append result.append(String(i)) //0.566s 5894.979kB //Plus Equal result += String(i) //0.570s 5894.979kB //NSMutableString result.append(String(i)) //0.751s 5891.694kB 

*Note about Convert Int to String

Source code

import XCTest class StringTests: XCTestCase { let count = 1_000_000 let metrics: [XCTMetric] = [ XCTClockMetric(), XCTMemoryMetric() ] let measureOptions = XCTMeasureOptions.default override func setUp() { measureOptions.iterationCount = 5 } func testAppend() { var result = "" measure(metrics: metrics, options: measureOptions) { for i in 0...count { result.append(String(i)) } } } func testPlusEqual() { var result = "" measure(metrics: metrics, options: measureOptions) { for i in 0...count { result += String(i) } } } func testPlus() { var result = "" measure(metrics: metrics, options: measureOptions) { for i in 0...count { result = result + String(i) } } } func testInterpolation() { var result = "" measure(metrics: metrics, options: measureOptions) { for i in 0...count { result = "\(result)\(i)" } } } //Up to 10_000 func testNSString() { var result: NSString = "" measure(metrics: metrics, options: measureOptions) { for i in 0...count { result = NSString(format: "%@%i", result, i) } } } func testNSMutableString() { let result = NSMutableString() measure(metrics: metrics, options: measureOptions) { for i in 0...count { result.append(String(i)) } } } } 

You could use SwiftString (https://github.com/amayne/SwiftString) to do this.

"".join(["string1", "string2", "string3"]) // "string1string2string" " ".join(["hello", "world"]) // "hello world" 

DISCLAIMER: I wrote this extension

In Swift 5 apple has introduces Raw Strings using # symbols.

Example:

print(#"My name is "XXX" and I'm "28"."#) let name = "XXX" print(#"My name is \#(name)."#) 

symbol # is necessary after \. A regular \(name) will be interpreted as characters in the string.