How do I concatenate strings in Swift

Question

How to concatenate string in Swift   In Objective-C we do like  NSString  string     Swift   NSString  resultStr    string stringByAppendingString    is a new Programming Language      or  NSString  resultStr  NSString stringWithFormat      is a new Programming Language  string     But I want to do this in Swift-language

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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

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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

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You can now use stringByAppendingString in Swift   var string    Swift  var resultString   string stringByAppendingString   is new Programming Language

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Swift 4 2 You can also use an extension  extension Array where Element    String        func compactConcate separator  String  - gt  String           return self compactMap    0   filter     0 isEmpty   joined separator  separator           Use  label text    m firstName  m lastName  compactConcate separator   quot   quot    Result   quot The Man quot   quot The quot   quot Man quot

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let the string    Swift  let resultString      the string  is a new Programming Language

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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

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Very Simple   let StringA    Hello  let StringB    World  let ResultString      StringA   StringB   println  Concatenated result     ResultString

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You can concatenate strings a number of ways   let a    Hello  let b    World   let first   a          b let second      a     b     You could also do   var c    Hello  c       World    I m sure there are more ways too   Bit of description  let creates a constant   sort of like an NSString   You can t change its value once you have set it  You can still add it to other things and create new variables though   var creates a variable   sort of like NSMutableString  so you can change the value of it  But this has been answered several times on Stack Overflow   see difference between let and var    Note  In reality let and var are very different from NSString and NSMutableString but it helps the analogy

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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    quot John  Jane quot  myClassmates     quot   Mark quot     add a new Classmate    Result   quot John  Jane  Mark quot   Different Strings If we want to combine different Strings together  for instance  let oldClassmates    quot John  Jane quot   let newClassmate    quot Mark quot   We can use any of the following  1  Using   let myClassmates   oldClassmates    quot    quot    newClassmate    Result   quot John  Jane  Mark quot   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    quot   oldClassmates     newClassmate  quot     Result   quot John  Jane  Mark quot   3  Appending let myClassmates   oldClassmates appending newClassmate     Result   quot John  Jane  Mark quot   Refer to Strings  amp  Characters from the Swift Book for more  Update  Tested on Swift 5 1

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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

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This will work too   var string    swift  var resultStr   string     is a new Programming Language

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To print the combined string using   Println    string1   string2      or String3 stores the output of combination of 2 strings  let strin3      string1   string2

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var language    Swift   var resultStr      language  is a new programming language

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Several words about performance UI Testing Bundle on iPhone 7 real device  with iOS 14 var result    quot  quot  for i in 0   count        lt concat operation gt      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    quot   result   i  quot                            0 164s 16 384kB    NSString result   NSString format   quot    i quot   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 - gt  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    quot  quot          measure metrics  metrics  options  measureOptions                for i in 0   count                   result append String i                                           func testPlusEqual             var result    quot  quot          measure metrics  metrics  options  measureOptions                for i in 0   count                   result    String i                                         func testPlus             var result    quot  quot          measure metrics  metrics  options  measureOptions                for i in 0   count                   result   result   String i                                         func testInterpolation             var result    quot  quot          measure metrics  metrics  options  measureOptions                for i in 0   count                   result    quot   result   i  quot                                           Up to 10 000     func testNSString             var result  NSString     quot  quot          measure metrics  metrics  options  measureOptions                for i in 0   count                   result   NSString format   quot    i quot   result  i                                         func testNSMutableString             let result   NSMutableString           measure metrics  metrics  options  measureOptions                for i in 0   count                   result append String i

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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

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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

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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

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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

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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

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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

[string] How do I concatenate strings in Swift?

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