Find an object in array

Question

Does Swift have something like   findWhere in Underscore js   I have an array of structs of type T and would like to check if array contains a struct object whose name property is equal to Foo   Tried to use find   and filter   but they only work with primitive types  e g  String or Int  Throws an error about not conforming to Equitable protocol or something like that

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You can filter the array and then just pick the first element  as shown in Find Object with Property in Array   Or you define a custom extension  extension Array           Returns the first element satisfying the predicate  or  nil         if there is no matching element      func findFirstMatching lt L   BooleanType gt  predicate  T - gt  L  - gt  T            for item in self               if predicate item                    return item    found                                 return nil    not found           Usage example   struct T       var name   String    let array    T name   bar    T name   baz    T name   foo     if let item   array findFirstMatching     0 name     foo               item is the first matching array element   else          not found       In Swift 3 you can use the existing first where   method  as mentioned in a comment    if let item   array first where     0 name     foo              item is the first matching array element   else          not found

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Another way to get access to array index of  Any  is by declaring your object   import Foundation class Model  NSObject

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Use contains   var yourItem YourType  if contains yourArray  item       yourItem   item     Or you could try what Martin pointed you at  in the comments and give filter another try  Find Object with Property in Array

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Swift 2 or later  You can combine indexOf and map to write a  find element  function in a single line   let array    T name   foo    T name   Foo    T name   FOO    let foundValue   array indexOf    0 name     Foo    map   array  0    print foundValue     Prints  T name   Foo      Using filter   first looks cleaner  but filter evaluates all the elements in the array  indexOf   map looks complicated  but the evaluation stops when the first match in the array is found  Both the approaches have pros and cons

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Swift 3  you can use index where   in Swift 3  func index where predicate   noescape Element throws - gt  Bool  rethrows - gt  Int    example  if let i   theArray index where    0 name     Foo          return theArray i

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For example  if we had an array of numbers   let numbers    2  4  6  8  9  10    We could find the first odd number like this   let firstOdd   numbers index    0   2    1     That will send back 4 as an optional integer  because the first odd number  9  is at index four

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SWIFT 5  Check if the element exists  if array contains where    0 name     foo            it exists  do something   else        item could not be found     Get the element  if let foo   array first where    0 name     foo            do something with foo   else         item could not be found     Get the element and its offset  if let foo   array enumerated   first where    0 element name     foo            do something with foo offset and foo element   else         item could not be found     Get the offset  if let fooOffset   array firstIndex where    0 name     foo             do something with fooOffset   else          item could not be found

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Swift 3  if yourArray contains item         item found  do what you want   else       item not found     yourArray append item

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Use Dollar which is Lo-Dash or Underscore js for Swift   import Dollar  let found     find array     0 name     Foo

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You can use the index method available on Array with a predicate  see Apple s documentation here    func index where predicate   Element  throws - gt  Bool  rethrows - gt  Int    For your specific example this would be   Swift 5 0  if let i   array firstIndex where     0 name     Foo           return array i      Swift 3 0  if let i   array index where     0 name    Foo          return array i      Swift 2 0  if let i   array indexOf    0 name    Foo          return array i

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FWIW  if you don t want to use custom function or extension  you can   let array            if let found   find array map    0 name      Foo         let obj   array found      This generates name array first  then find from it   If you have huge array  you might want to do   if let found   find lazy array  map    0 name      Foo         let obj   array found      or maybe   if let found   find lazy array  map    0 name     Foo      true        let obj   array found

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Swift 3  If you need the object use   array first  0 name     Foo      If you have more than one object named  Foo  then first will return the first object from an unspecified ordering

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Swift 3   You can use Swifts built in functionality to find custom objects in an Array   First you must make sure your custom object conforms to the  Equatable protocol   class Person   Equatable      lt --- Add Equatable protocol     let name  String     var age  Int      init name  String  age  Int            self name   name         self age   age              Add Equatable functionality      static func     lhs  Person  rhs  Person  - gt  Bool           return  lhs name    rhs name            With Equatable functionality added to your object   Swift will now show you additional properties you can use on an array     create new array and populate with objects  let p1   Person name   Paul   age  20  let p2   Person name   Mike   age  22  let p3   Person name   Jane   age  33  var people    Person   p1 p2 p3      find index by object  let index   people index of  p2     finds Index of Mike    remove item by index  people remove at  index    removes Mike from array

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Swift 3 0  if let index   array index where     0 name     Foo           return array index      Swift 2 1   Filtering in object properties is now supported in swift 2 1  You can filter your array based on any value of the struct or class here is an example  for myObj in myObjList where myObj name     foo       object with name is foo     OR  for myObj in myObjList where myObj Id  gt  10      objects with Id is greater than 10

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For Swift 3   let index   array index where    0 name     foo

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Swift 4  Another way to achieve this using filter function  if let object   elements filter    0 title     quot title quot     first       print  quot found quot     else       print  quot not found quot

[ios] Find an object in array?

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