如何在swift中迭代数组

Im learning swift and am having a problem Iterating through an array. Here is what I'm trying to do:

我正在学习swift并且遇到问题迭代通过数组。这是我正在尝试做的事情:

func orderStringByOccurence(stringArray: [String]) -> [String: Int]{
    var stringDictionary: [String: Int] = [:]
    for i in 0...stringArray.count {
        if stringDictionary[stringArray[i]] == nil {
            stringDictionary[stringArray[i]] = 1
            stringDictionary
        } else {
            stringDictionary[stringArray[i]]! += 1
        }
    }
    return stringDictionary
}

I don't get an error until I try to call this function. Then I get this error:

在我尝试调用此函数之前,我没有收到错误。然后我收到这个错误:

EXC_BAD_INSTRUCTION (code=EXC_1386_INVOP, subcode=0x0)

EXC_BAD_INSTRUCTION(代码= EXC_1386_INVOP,子代码= 0x0)

I have tried debugging and found that i get the same error when i try this:

我试过调试,发现我尝试这个时遇到同样的错误:

for i in 0...arrayFromString.count{
    print(arrayFromString[i])
}

So how do I iterate through this array? Thanks for helping out a new

那么如何遍历这个数组呢?感谢您帮助解决新问题

3 个解决方案

#1

You need to change

你需要改变

for i in 0...arrayFromString.count

for i in 0..<arrayFromString.count

As it is now, you iterate through the array and then one past the end.

就像现在一样,你遍历数组,然后遍历结束。

You can also use a different style of for loop, which is perhaps a little better:

你也可以使用不同风格的for循环,这可能会更好一些:

func orderStringByOccurence(stringArray: [String]) -> [String: Int] {
    var stringDictionary: [String: Int] = [:]
    for string in stringArray {
        if stringDictionary[string] == nil {
            stringDictionary[string] = 1
        } else {
            stringDictionary[string]! += 1
        }
    }
    return stringDictionary
}

Also, you can simplify your logic a bit:

此外,您可以稍微简化您的逻辑:

for string in stringArray {
    stringDictionary[string] = stringDictionary[string] ?? 0 + 1
}

#2

A few more approaches:

还有一些方法:

let array = ["1", "2", "3"]

You can use forEach with trailing closure syntax:

您可以将forEach与尾随闭包语法一起使用:

array.forEach { item in
    print(item)
}

You can use the $0 shorthand:

您可以使用$ 0速记:

array.forEach {
    print($0)
}

And if you need the indexes, you can use enumerate():

如果需要索引,可以使用enumerate():

array.enumerate().forEach { itemTuple in
    print("\(itemTuple.element) is at index \(itemTuple.index)")
}

#3

It seems you're out of index. A more swift-like approach would be in my opinion not to use the count but to do range-based.

看来你已经没有索引了。在我看来,更快速的方法是不使用计数而是基于范围。

var stringArray = ["1", "2", "3"]
for string in stringArray
{
    print(string)
}

#1