swift 3获取子字符串的起始索引（作为int） [英] swift 3 get start index (as int) of substring

问题描述

我想获得字符串中子字符串的开始和结束位置。示例：在字符串这是我的名字;如果我提供字符串this，我想知道起始索引是4，结束索引是7。

I would like to get the start and end position of a substring within a string. Example: in the string "hi this is my name"; if I provide the string "this" I would like to know the start index is 4 and end index is 7.

我找到了几个链接，包括这个：

I found several links, including this one:

Swift：获取开始索引字符串中的子字符串
a-substring-in-a-string

Swift: get index of start of a substring in a string a-substring-in-a-string

但它在swift 3中不起作用现在称为范围。

But it doesn´t work in swift 3 as the method is now called range.

我现在正在使用它：

let range = mystring.range(of: "StringSearch")?.lowerBound

返回此

Swift.String.UnicodeScalarView.Index(_position: 15), _countUTF16: 1))

我无法获得整数的位置，因为这是一个指数。

And I cannot obtain the position as an integer as this is an index.

In总结一下，我想在一个int类型的变量中有一个位置，在这种情况下是15。

In summary, I would like to have in a variable of type int the position, in this case 15.

任何人都可以帮助我吗？

Can anyone help me?

谢谢大家。

推荐答案

距离（从：到：） 方法字符串计算两个<$ c $之间的差额
c> String.Index values：

The distance(from:to:) method of String computes the difference between two String.Index values:

let mystring = "hi this is my name"
if let range = mystring.range(of: "this") {
    let startPos = mystring.distance(from: mystring.startIndex, to: range.lowerBound)
    let endPos = mystring.distance(from: mystring.startIndex, to: range.upperBound)
    print(startPos, endPos) // 3 7
}

实际上它只是将调用转发给字符串的 CharacterView ，所以
上面的结果与

Actually it just forwards the call to the string's CharacterView, so the above gives the same result as

let mystring = "hi this is my name"
if let range = mystring.range(of: "this") {
    let startPos = mystring.characters.distance(from: mystring.characters.startIndex, to: range.lowerBound)
    let endPos = mystring.characters.distance(from: mystring.characters.startIndex, to: range.upperBound)
    print(startPos, endPos) // 3 7
}

---

如果您需要所有次出现string：

---

If you need all occurrences of the string:

let mystring = "this is this and that is that"
var searchPosition = mystring.startIndex
while let range = mystring.range(of: "this", range: searchPosition..<mystring.endIndex) {
    let startPos = mystring.distance(from: mystring.startIndex, to: range.lowerBound)
    let endPos = mystring.distance(from: mystring.startIndex, to: range.upperBound)
    print(startPos, endPos)

    searchPosition = range.upperBound
}

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