swift 3获取子字符串的起始索引(作为int)

Question

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"嗨,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.

我发现了几个链接,包括这个链接:

Swift:获取字符串 a-substring-in-a-string中子字符串的起始索引

但它在swift 3中不起作用,因为该方法现在称为范围.

我现在用这个:

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,因为这是一个索引.

总之,我想在一个int类型的变量中使用位置,在本例中为15.

谁能帮我？

感谢大家.

Answer 1

计算两个值之间差异的distance(from:to:)方法:StringString.Index

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CharacterView,所以上面给出了相同的结果

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
}

如果您需要所有出现的字符串:

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
}