How to check if an element is in an array

Question

In Swift  how can I check if an element exists in an array  Xcode does not have any suggestions for contain  include  or has  and a quick search through the book turned up nothing  Any idea how to check for this  I know that there is a method find that returns the index number  but is there a method that returns a boolean like ruby s  include    Example of what I need   var elements    1 2 3 4 5  if elements contains 5        do something

User · Answer

Swift 4 5  Another way to achieve this is with the filter function     var elements    1 2 3 4 5  if let object   elements filter    0    5    first       print  found     else       print  not found

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Here is my little extension I just wrote to check if my delegate array contains a delegate object or not  Swift 2      It Also works with value types like a charm   extension Array       func containsObject object  Any  - gt  Bool               if let anObject  AnyObject   object as  AnyObject                       for obj in self                               if let anObj  AnyObject   obj as  AnyObject                                       if anObj     anObject   return true                                                     return false           If you have an idea how to optimize this code  than just let me know

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Just in case anybody is trying to find if an indexPath is among the selected ones  like in a UICollectionView or UITableView cellForItemAtIndexPath functions            var isSelectedItem   false     if let selectedIndexPaths   collectionView indexPathsForSelectedItems   as   NSIndexPath           if contains selectedIndexPaths  indexPath                isSelectedItem   true

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An array that contains a property that equals to yourArray contains where    0 propertyToCheck    value     Returns boolean

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Swift 3   Check if an element exists in an array  fulfilling some criteria   and if so  proceed working with the first such element  If the intent is    To check whether an element exist in an array   fulfils some boolean criteria  not necessarily equality testing   And if so  proceed and work with the first such element    Then an alternative to contains     as blueprinted Sequence is to first where   of Sequence   let elements    1  2  3  4  5   if let firstSuchElement   elements first where     0    4          print firstSuchElement     4                In this contrived example  its usage might seem silly  but it s very useful if querying arrays of non-fundamental element types for existence of any elements fulfilling some condition  E g   struct Person       let age  Int     let name  String     init   age  Int    name  String            self age   age         self name   name          let persons    Person 17   Fred      Person 16   Susan                   Person 19   Hannah    Person 18   Sarah                   Person 23   Sam       Person 18   Jane     if let eligableDriver   persons first where     0 age  gt   18          print    eligableDriver name  can possibly drive the rental car in Sweden                    Hannah can possibly drive the rental car in Sweden   let daniel   Person 18   Daniel   if let sameAgeAsDaniel   persons first where     0 age    daniel age          print    sameAgeAsDaniel name  is the same age as   daniel name                     Sarah is the same age as Daniel    Any chained operations using  filter       some condition   first can favourably be replaced with first where    The latter shows intent better  and have performance advantages over possible non-lazy appliances of  filter  as these will pass the full array prior to extracting the  possible  first element passing the filter     Check if an element exists in an array  fulfilling some criteria   and if so  remove the first such element  A comment below queries      How can I remove the firstSuchElement from the array    A similar use case to the one above is to remove the first element that fulfils a given predicate  To do so  the index where   method of Collection  which is readily available to array collection  may be used to find the index of the first element fulfilling the predicate  whereafter the index can be used with the remove at   method of Array to  possible  given that it exists  remove that element   var elements     a    b    c    d    e    a    b    c    if let indexOfFirstSuchElement   elements index where     0     c           elements remove at  indexOfFirstSuchElement      print elements       a    b    d    e    a    b    c       Or  if you d like to remove the element from the array and work with  apply Optional s map     method to conditionally  for  some      return from index where    use the result from index where   to remove and capture the removed element from the array  within an optional binding clause    var elements     a    b    c    d    e    a    b    c    if let firstSuchElement   elements index where     0     c          map   elements remove at   0               if we enter here  the first such element have now been        remove from the array     print elements       a    b    d    e    a    b    c           and we may work with it     print firstSuchElement     c     Note that in the contrived example above the array members are simple value types  String instances   so using a predicate to find a given member is somewhat over-kill  as we might simply test for equality using the simpler index of   method as shown in  DogCoffee s answer  If applying the find-and-remove approach above to the Person example  however  using index where   with a predicate is appropriate  since we no longer test for equality but for fulfilling a supplied predicate

User · Answer

The simplest way to accomplish this is to use filter on the array   let result   elements filter    0  5     result will have the found element if it exists and will be empty if the element does not exist  So simply checking if result is empty will tell you whether the element exists in the array  I would use the following   if result isEmpty          element does not exist in array   else          element exists

User · Answer

what about using a hash table for the job  like this   first  creating a  hash map  generic function  extending the Sequence protocol   extension Sequence where Element  Hashable        func hashMap   - gt   Element  Int            var dict   Element  Int                for  i  value  in self enumerated                 dict value    i                   return dict           This extension will work as long as the items in the array conform to Hashable  like integers or strings  here is the usage     let numbers   Array 0   50   let hashMappedNumbers   numbers hashMap    let numToDetect   35  let indexOfnumToDetect   hashMappedNumbers numToDetect     returns the index of the item and if all the elements in the array are different  it will work to get the index of the object   print indexOfnumToDetect     prints 35   But for now  let s just focus in check if the element is in the array   let numExists   indexOfnumToDetect    nil    if the key does not exist  means the number is not contained in the collection   print numExists     prints true

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For those who came here looking for a find and remove an object from an array   Swift 1  if let index   find itemList  item        itemList removeAtIndex index      Swift 2  if let index   itemList indexOf item        itemList removeAtIndex index      Swift 3  4  if let index   itemList index of  item        itemList remove at  index      Swift 5 2  if let index   itemList firstIndex of  item        itemList remove at  index

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I used filter   let results   elements filter   el in el    5   if results count  gt  0          any matching items are in results   else          not found     If you want  you can compress that to  if elements filter   el in el    5    count  gt  0       Hope that helps     Update for Swift 2  Hurray for default implementations   if elements contains 5           any matching items are in results   else          not found

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If you are checking if an instance of a custom class or struct is contained in an array  you ll need to implement the Equatable protocol before you can use  contains myObject    For example   struct Cup  Equatable       let filled Bool    static func    lhs Cup  rhs Cup  - gt  Bool      Implement Equatable     return lhs filled    rhs filled     then you can do   cupArray contains myCup    Tip  The    override should be at the global level  not within your class struct

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Swift    If you are not using object then you can user this code for contains   let elements     10  20  30  40  50   if elements contains 50        print  true        If you are using NSObject Class in swift  This variables is according to my requirement  you can modify for your requirement    var cliectScreenList    ATModelLeadInfo    var cliectScreenSelectedObject  ATModelLeadInfo    This is for a same data type      0 user id    cliectScreenSelectedObject user id     If you want to AnyObject type         0 user id         cliectScreenSelectedObject user id       Full condition   if cliectScreenSelected contains     0 user id    cliectScreenSelectedObject user id        false        cliectScreenSelected append cliectScreenSelectedObject       print  Object Added      else        print  Object already exists

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Swift 4 2   You can easily verify your instance is an array or not by the following function    func verifyIsObjectOfAnArray lt T gt    object  T  - gt  Bool      if let     object as   T          return true          return false     Even you can access it as follows  You will receive nil if the object wouldn t be an array    func verifyIsObjectOfAnArray lt T gt    object  T  - gt   T        if let array   object as   T          return array          return nil

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As of Swift 2 1 NSArrays have containsObjectthat can be used like so   if myArray containsObject objectImCheckingFor         myArray has the objectImCheckingFor

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Array let elements    1  2  3  4  5  5   Check elements presence elements contains 5     true  Get elements index elements firstIndex of  5     4 elements firstIndex of  10     nil  Get element count let results   elements filter   element in element    5   results count    2

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Swift 2  3  4  5   let elements    1  2  3  4  5  if elements contains 5        print  yes       contains   is a protocol extension method of SequenceType  for sequences of Equatable elements  and not a global method as in earlier releases   Remarks     This contains   method requires that the sequence elements adopt the Equatable protocol  compare e g  Andrews s answer  If the sequence elements are instances of a NSObject subclass then you have to override isEqual   see NSObject subclass in Swift  hash vs hashValue  isEqual vs     There is another     more general     contains   method which does not require the elements to be equatable and takes a predicate as an  argument  see e g  Shorthand to test if an object exists in an array for Swift     Swift older versions    let elements    1 2 3 4 5  if contains elements  5        println  yes

User · Answer

if user find particular array elements  then use below  code same as integer value   var arrelemnts     sachin    test    test1    test3     if arrelemnts contains  test        print  found      else      print  not found

User · Answer

Use this extension   extension Array       func contains lt T where T   Equatable gt  obj  T  - gt  Bool           return self filter   0 as  T    obj   count  gt  0           Use as   array contains 1    Updated for Swift 2 3  Note that as of Swift 3  or even 2   the extension is no longer necessary as the global contains function has been made into a pair of extension method on Array  which allow you to do either of   let a     1  2  3  4    a contains 2                 gt  true  only usable if Element   Equatable  a contains    0  lt  1          gt  false

[arrays] How to check if an element is in an array

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