以防有人遇到这种问题

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

一定要这么做

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

then

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

这些方法对我都适用

这是我对Swift 4的解决方案:

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
            $0 === tuesday
        })

斯威夫特5

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

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

例二

let index = alphabets.firstIndex(where: {$0 == "A"})

Example2

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

如果你还在使用Swift 1.x

然后尝试,

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

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

Swift 2更新:

sequence.contains(element):如果给定序列(如 数组)包含指定的元素。

斯威夫特1:

如果你只是检查一个元素是否包含在一个数组中，也就是说，只是获取一个布尔指示符，使用contains(sequence, element)而不是find(array, element):

contains(sequence, element):如果给定序列(如 数组)包含指定的元素。

请看下面的例子:

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.   
}

斯威夫特4。如果数组包含类型为[String: AnyObject]的元素。因此，要查找元素的索引，请使用下面的代码

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)

或者如果你想找到索引的基础上的关键字从字典。这里数组包含对象的模型类和我匹配id属性。

   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($0.store_id) == storeId }! // Array contains models and finding specific one