如何在Swift中找到列表项的索引？

#1 楼

let arr:Array = ["a","b","c"]
find(arr, "c")!              // 2
find(arr, "d")               // nil

let arr = ["a","b","c"]

let indexOfA = arr.indexOf("a") // 0
let indexOfB = arr.indexOf("b") // 1
let indexOfD = arr.indexOf("d") // nil

let arr2 = [1,2,3,4,5,6,7,8,9,10]
let indexOfFirstGreaterThanFive = arr2.indexOf({
let indexOfA = arr.index(of: "a")
 > 5}) // 5
let indexOfFirstGreaterThanOneHundred = arr2.indexOf({
let index = cells.index(where: { (item) -> Bool in
  item.foo == 42 // test if this is the item you're looking for
})
 > 100}) // nil

let arr = ["a","b","c","a"]

let indexOfA = arr.firstIndex(of: "a") // 0
let indexOfB = arr.lastIndex(of: "a") // 3

#2 楼

 let index = someArray.firstIndex{class === someObject}
 

 === 

 == 

#3 楼

var myList = [1, 2, 3, 4]
var filtered = myList.filter { 
filtered.count // <= returns 1
 == 3 }  // <= returns [3]

myList.filter { 
var found: Int?  // <= will hold the index if it was found, or else will be nil
for i in (0..x.count) {
    if x[i] == 3 {
        found = i
    }
}
 == 3 }.count > 0  // <= returns true if the array includes 3

extension Array {
    func find(includedElement: T -> Bool) -> Int? {
        for (idx, element) in enumerate(self) {
            if includedElement(element) {
                return idx
            }
        }
        return nil
    }
}

myList.find { q4312078q == 3 }
// returns the index position of 3 or nil if not found

#4 楼

func firstIndex(of element: Element) -> Int?

var alphabets = ["A", "B", "E", "D"]

let index = alphabets.firstIndex(where: {
if let i = alphabets.firstIndex(of: "E") {
    alphabets[i] = "C" // i is the index
}
print(alphabets)
// Prints "["A", "B", "C", "D"]"
 == "A"})

#5 楼

let array = ["apple", "dog", "log"]

let indexes = array.enumerated().filter {
    
let array = ["apple", "dog", "log"]

let indexes = array.enumerate().filter {
    q4312078q.element.containsString("og")
    }.map{q4312078q.index}

print(indexes)
.element.contains("og")
    }.map{q4312078q.offset}

print(indexes)

#6 楼

import Foundation

func ==(l: MyClass, r: MyClass) -> Bool {
  return l.id == r.id
}

class MyClass: Equtable {
    init(id: String) {
        self.msgID = id
    }

    let msgID: String
}

let item = MyClass(3)
let itemList = [MyClass(1), MyClass(2), item]
let idx = itemList.indexOf(item)

printl(idx)

#7 楼

array.firstIndex(where: {q4312078q == "person1"})

#8 楼

var languages = ["Swift", "Objective-C"]
contains(languages, "Swift") == true
contains(languages, "Java") == false
contains([29, 85, 42, 96, 75], 42) == true
if (contains(languages, "Swift")) {
  // Use contains in these cases, instead of find.   
}

#9 楼

var array = [[String: AnyObject]]()// Save your data in array
let objectAtZero = array[0] // get first object
let index = (self.array as NSArray).index(of: objectAtZero)

   let userId = 20
    if let index = array.index(where: { (dict) -> Bool in
           return dict.id == userId // Will found index of matched id
    }) {
    print("Index found")
    }
OR
      let storeId = Int(surveyCurrent.store_id) // Accessing model key value
      indexArrUpTo = self.arrEarnUpTo.index { Int(q4312078q.store_id) == storeId }! // Array contains models and finding specific one

#10 楼

class Photo : Equatable{
    var imageURL: URL?
    init(imageURL: URL){
        self.imageURL = imageURL
    }

    static func == (lhs: Photo, rhs: Photo) -> Bool{
        return lhs.imageURL == rhs.imageURL
    }
}

let index = self.photos.index(of: aPhoto)

#11 楼

array.firstIndex(where: { q4312078q == searchedItem })

#12 楼

var array = ["0","1","2","3"]

if let index = array.indexOf("1") {
   array.removeAtIndex(index)
}

print(array) // ["0","2","3"]

var array = ["0","1","2","3"]

if let index = array.index(of: "1") {
    array.remove(at: index)
}
array.remove(at: 1)

#13 楼

#14 楼

let monday = Day(name: "M")
let tuesday = Day(name: "T")
let friday = Day(name: "F")

let days = [monday, tuesday, friday]

let index = days.index(where: { 
            //important to test with === to be sure it's the same object reference
            q4312078q === tuesday
        })

#15 楼

$.indexOf([1, 2, 3, 1, 2, 3], value: 2) 
=> 1

#16 楼

let testArray = ["A","B","C"]

let indexOfA = find(testArray, "A") 
let indexOfB = find(testArray, "B")
let indexOfC = find(testArray, "C")

#17 楼

let index = array.firstIndex{q4312078q == value}

#18 楼

func find(objecToFind: String?) -> Int? {
   for i in 0...arrayName.count {
      if arrayName[i] == objectToFind {
         return i
      }
   }
return nil
}

arrayName.remove(at: (find(objecToFind))!)

#19 楼

Cannot invoke initializer for type 'Int' with an argument list of type '(Array<Element>.Index?)'

extension Int {
    var toInt: Int {
        return self
    }
}

guard let finalIndex = index?.toInt else {
    return false
}

#20 楼

var names: [String] = ["jack", "rose", "jill"]

names.index(of: "rose") // returns 1

#21 楼

extension Array where Array.Element: AnyObject {

    func index(ofElement element: Element) -> Int? {
        for (currentIndex, currentElement) in self.enumerated() {
            if currentElement === element {
                return currentIndex
            }
        }
        return nil
    }
}

#22 楼

let cardNumber = cardButtons.index(of: sender)