How do I concatenate or merge arrays in Swift

Question

If there are two arrays created in swift like this   var a  CGFloat     1  2  3  var b  CGFloat     4  5  6    How can they be merged to  1  2  3  4  5  6

User · Answer

With Swift 5  according to your needs  you may choose one of the six following ways to concatenate merge two arrays      1  Merge two arrays into a new array with Array s         generic operator  Array has a         generic operator          has the following declaration      Creates a new collection by concatenating the elements of a collection and a sequence    static func    lt Other gt  lhs  Array lt Element gt   rhs  Other  - gt  Array lt Element gt  where Other   Sequence  Self Element    Other Element   The following Playground sample code shows how to merge two arrays of type  Int  into a new array using         generic operator   let array1    1  2  3  let array2    4  5  6   let flattenArray   array1   array2 print flattenArray     prints  1  2  3  4  5  6       2  Append the elements of an array into an existing array with Array s          generic operator  Array has a          generic operator           has the following declaration      Appends the elements of a sequence to a range-replaceable collection    static func     lt Other gt  lhs  inout Array lt Element gt   rhs  Other  where Other   Sequence  Self Element    Other Element   The following Playground sample code shows how to append the elements of an array of type  Int  into an existing array using          generic operator   var array1    1  2  3  let array2    4  5  6   array1    array2 print array1     prints  1  2  3  4  5  6       3  Append an array to another array with Array s append contentsOf   method  Swift Array has an append contentsOf   method  append contentsOf   has the following declaration      Adds the elements of a sequence or collection to the end of this collection    mutating func append lt S gt  contentsOf newElements  S  where S   Sequence  Self Element    S Element   The following Playground sample code shows how to append an array to another array of type  Int  using append contentsOf   method   var array1    1  2  3  let array2    4  5  6   array1 append contentsOf  array2  print array1     prints  1  2  3  4  5  6       4  Merge two arrays into a new array with Sequence s flatMap     method  Swift provides a flatMap     method for all types that conform to Sequence protocol  including Array   flatMap     has the following declaration      Returns an array containing the concatenated results of calling the given transformation with each element of this sequence    func flatMap lt SegmentOfResult gt    transform   Self Element  throws - gt  SegmentOfResult  rethrows - gt   SegmentOfResult Element  where SegmentOfResult   Sequence   The following Playground sample code shows how to merge two arrays of type  Int  into a new array using flatMap     method   let array1    1  2  3  let array2    4  5  6   let flattenArray    array1  array2  flatMap    element   Int   - gt   Int  in     return element    print flattenArray     prints  1  2  3  4  5  6       5  Merge two arrays into a new array with Sequence s joined   method  and Array s init     initializer  Swift provides a joined   method for all types that conform to Sequence protocol  including Array   joined   has the following declaration      Returns the elements of this sequence of sequences  concatenated    func joined   - gt  FlattenSequence lt Self gt    Besides  Swift Array has a init     initializer  init     has the following declaration      Creates an array containing the elements of a sequence    init lt S gt    s  S  where Element    S Element  S   Sequence   Therefore  the following Playground sample code shows how to merge two arrays of type  Int  into a new array using joined   method and init     initializer   let array1    1  2  3  let array2    4  5  6   let flattenCollection    array1  array2  joined      type  FlattenBidirectionalCollection lt  Array lt Int gt   gt  let flattenArray   Array flattenCollection  print flattenArray     prints  1  2  3  4  5  6       6  Merge two arrays into a new array with Array s reduce       method  Swift Array has a reduce       method  reduce       has the following declaration      Returns the result of combining the elements of the sequence using the given closure    func reduce lt Result gt    initialResult  Result    nextPartialResult   Result  Element  throws - gt  Result  rethrows - gt  Result   The following Playground code shows how to merge two arrays of type  Int  into a new array using reduce       method   let array1    1  2  3  let array2    4  5  6   let flattenArray    array1  array2  reduce        result   Int   element   Int   - gt   Int  in     return result   element    print flattenArray     prints  1  2  3  4  5  6

User · Answer

To complete the list of possible alternatives  reduce could be used to implement the behavior of flatten   var a     a    b    c    var b     d    e    f    let res    a  b  reduce    combine      The best alternative  performance memory-wise  among the ones presented is simply flatten  that just wrap the original arrays lazily without creating a new array structure   But notice that flatten does not return a LazyCollection  so that lazy behavior will not be propagated to the next operation along the chain  map  flatMap  filter  etc        If lazyness makes sense in your particular case  just remember to prepend or append a  lazy to flatten    for example  modifying Tomasz sample this way   let c    a  b  lazy flatten

User · Answer

Swift 5 Array Extension extension Array where Element  Sequence       func join   - gt  Array lt Element Element gt            return self reduce                 Example  let array     1 2 3    4 5 6    7 8 9   print array join       result   1  2  3  4  5  6  7  8  9

User · Answer

var arrayOne    1 2 3  var arrayTwo    4 5 6    if you want result as    1 2 3  4 5 6    arrayOne append arrayTwo    above code will convert arrayOne as a single element and add it to the end of arrayTwo   if you want result as    1  2  3  4  5  6  then   arrayOne append contentsOf  arrayTwo    above code will add all the elements of arrayOne at the end of arrayTwo   Thanks

User · Answer

You can concatenate the arrays with    building a new array   let c   a   b print c      1 0  2 0  3 0  4 0  5 0  6 0    or append one array to the other with     or append    a    b     Or  a append contentsOf  b      Swift 3 a appendContentsOf b        Swift 2 a extend b                  Swift 1 2  print a      1 0  2 0  3 0  4 0  5 0  6 0

User · Answer

If you want the second array to be inserted after a particular index you can do this  as of Swift 2 2    let index   1 if 0     a count    index        a index   lt index    b 0   lt b count    print a      1 0  4 0  5 0  6 0  2 0  3 0

User · Answer

Swift 3 0  You can create a new array by adding together two existing arrays with compatible types with the addition operator      The new array s type is inferred from the type of the two array you add together   let arr0   Array repeating  1  count  3      1  1  1  let arr1   Array repeating  2  count  6    2  2  2  2  2  2  let arr2   arr0   arr1    1  1  1  2  2  2  2  2  2    this is the right results of above codes

User · Answer

Swift 4 X   easiest way I know is to just use the   sign  var Array1     Item 1    Item 2   var Array2     Thing 1    Thing 2    var Array3   Array1   Array2     Array 3 will just be them combined

User · Answer

Marge array that are different data types    var arrayInt    Int    arrayInt append 6  var testArray     a  true 3  b   as  Any  testArray append someInt    Output      a   true  3   b    hi   3   6

User · Answer

Here s the shortest way to merge two arrays    var array1    1 2 3   let array2    4 5 6    Concatenate merge them  array1    array2 New value of array1 is  1 2 3 4 5 6

User · Answer

Similarly  with dictionaries of arrays one can   var dict1    String  Int     var dict2    String  Int     dict1  key      1 2 3  dict2  key      4 5 6  dict1  key     dict1  key      dict2  key    print dict1  key       and you can iterate over dict1 and add dict2 if the  key  matches

User · Answer

If you are not a big fan of operator overloading  or just more of a functional type      use flatMap let result           merge    me           We    shall    unite          magic     flatMap    0      Output    merge    me    We    shall    unite    magic           or reduce   1   2   3   reduce           Output   1  2  3

User · Answer

My favorite method since Swift 2 0 is flatten  var a  CGFloat     1  2  3  var b  CGFloat     4  5  6   let c    a  b  flatten     This will return FlattenBidirectionalCollection so if you just want a CollectionType this will be enough and you will have lazy evaluation for free  If you need exactly the Array you can do this   let c   Array  a  b  flatten

[arrays] How do I concatenate or merge arrays in Swift?

#1. Merge two arrays into a new array with `Array`'s `+(_:_:)` generic operator

#2. Append the elements of an array into an existing array with `Array`'s `+=(_:_:)` generic operator

#3. Append an array to another array with `Array`'s `append(contentsOf:)` method

#4. Merge two arrays into a new array with `Sequence`'s `flatMap(_:)` method

#5. Merge two arrays into a new array with `Sequence`'s `joined()` method and `Array`'s `init(_:)` initializer

#6. Merge two arrays into a new array with `Array`'s `reduce(_:_:)` method

Examples related to arrays

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[arrays] How do I concatenate or merge arrays in Swift?

#1. Merge two arrays into a new array with Array's +(_:_:) generic operator

#2. Append the elements of an array into an existing array with Array's +=(_:_:) generic operator

#3. Append an array to another array with Array's append(contentsOf:) method

#4. Merge two arrays into a new array with Sequence's flatMap(_:) method

#5. Merge two arrays into a new array with Sequence's joined() method and Array's init(_:) initializer

#6. Merge two arrays into a new array with Array's reduce(_:_:) method