同时迭代两个数组

Question

我是 Swift 的新手。我一直在做Java编程。我有一个要在 Swift 中编码的场景。

以下代码使用 Java。我需要为以下场景编写 Swift 代码

// With String array - strArr1
String strArr1[] = {"Some1","Some2"}

String strArr2[] = {"Somethingelse1","Somethingelse2"}

for( int i=0;i< strArr1.length;i++){
    System.out.println(strArr1[i] + " - "+ strArr2[i]);
}

我在 swift 中有几个数组

var strArr1: [String] = ["Some1","Some2"]
var strArr2: [String] = ["Somethingelse1","Somethingelse2"]

for data in strArr1{
    println(data)
}

for data in strArr2{
    println(data)
}
// I need to loop over in single for loop based on index.

您能否就基于索引的循环语法提供您的帮助

Answer 1

for(var i = 0; i < strArr1.count ; i++)
{
    println(strArr1[i] + strArr2[i])
}

应该这样做。之前从未使用过 swift，因此请务必进行测试。

更新到最新的 Swift 语法

for i in 0..< strArr1.count {
    print(strArr1[i] + strArr2[i])
}

Answer 2

您也可以enumerate 遍历一个数组并使用索引查看第二个数组：

斯威夫特 1.2：

for (index, element) in enumerate(strArr1) {
    println(element)
    println(strArr2[index])
}

斯威夫特 2：

for (index, element) in strArr1.enumerate() {
    print(element)
    print(strArr2[index])
}

斯威夫特 3：

for (index, element) in strArr1.enumerated() {
    print(element)
    print(strArr2[index])
}

Answer 3

如果您仍想使用for in，可以使用Range。

var strArr1: [String] = ["Some1","Some2"]
var strArr2: [String] = ["Somethingelse1","Somethingelse2"]

for i in Range(start: 0, end: strArr1.count) {
    println(strArr1[i] + " - " + strArr2[i])
}

Answer 4

您可以使用zip()，它会创建 来自两个给定序列的对序列：

let strArr1 = ["Some1", "Some2"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]

for (e1, e2) in zip(strArr1, strArr2) {
    print("\(e1) - \(e2)")
}

序列仅枚举给定序列/数组的“公共元素”。如果它们的长度不同，那么附加的 较长的数组/序列的元素被简单地忽略。

Answer 5

试试这个：

zip([0,2,4,6], [1,3,5,7]).forEach {
    print($0,$1)
}

zip([0,2,4,6], [1,3,5,7]).forEach {
    print($0.0,$0.1)
}

Answer 6

使用 Swift 5，您可以使用以下 4 个 Playground 代码之一来解决您的问题。

---

#1。使用zip(_:_:)函数

在最简单的情况下，您可以使用zip(_:_:) 创建初始数组元素的新序列对（元组）。

let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]

let sequence = zip(strArr1, strArr2)

for (el1, el2) in sequence {
    print("\(el1) - \(el2)")
}

/*
 prints:
 Some1 - Somethingelse1
 Some2 - Somethingelse2
 */

---

#2。使用Array 的makeIterator() 方法和while 循环

使用简单的while循环和迭代器同时循环两个数组也很容易：

let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]

var iter1 = strArr1.makeIterator()
var iter2 = strArr2.makeIterator()

while let el1 = iter1.next(), let el2 = iter2.next() {
    print("\(el1) - \(el2)")
}

/*
 prints:
 Some1 - Somethingelse1
 Some2 - Somethingelse2
 */

---

#3。使用符合IteratorProtocol 的自定义类型

在某些情况下，您可能希望创建自己的类型来配对您的首字母数组的元素。这可以通过使您的类型符合IteratorProtocol 来实现。请注意，通过使您的类型也符合 Sequence 协议，您可以直接在 for 循环中使用它的实例：

struct TupleIterator: Sequence, IteratorProtocol {

    private var firstIterator: IndexingIterator<[String]>
    private var secondIterator: IndexingIterator<[String]>

    init(firstArray: [String], secondArray: [String]) {
        self.firstIterator = firstArray.makeIterator()
        self.secondIterator = secondArray.makeIterator()
    }

    mutating func next() -> (String, String)? {
        guard let el1 = firstIterator.next(), let el2 = secondIterator.next() else { return nil }
        return (el1, el2)
    }

}

let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]

let tupleSequence = TupleIterator(firstArray: strArr1, secondArray: strArr2)

for (el1, el2) in tupleSequence {
    print("\(el1) - \(el2)")
}

/*
 prints:
 Some1 - Somethingelse1
 Some2 - Somethingelse2
 */

---

#4。使用AnyIterator

作为前面示例的替代方法，您可以使用AnyIterator。以下代码显示了它在 Array 扩展方法中的可能实现：

extension Array {

    func pairWithElements(of array: Array) -> AnyIterator<(Element, Element)> {
        var iter1 = self.makeIterator()
        var iter2 = array.makeIterator()

        return AnyIterator({
            guard let el1 = iter1.next(), let el2 = iter2.next() else { return nil }
            return (el1, el2)
        })
    }

}

let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]

let iterator = strArr1.pairWithElements(of: strArr2)

for (el1, el2) in iterator {
    print("\(el1) - \(el2)")
}

/*
 prints:
 Some1 - Somethingelse1
 Some2 - Somethingelse2
 */

Answer 7

> Incase of unequal count 

let array1 = ["some1","some2"]
let array2 = ["some1","some2","some3"]

var iterated = array1.makeIterator()
let finalArray = array2.map({ 
                 let itemValue = iterated.next()
                 return "\($0)\(itemValue != nil ? "-"+itemValue! : EmptyString)" })

// 结果 : ["some1-some1","some2-some2","some3"]