获取字符串到特定字符 [英] Get the string up to a specific character

问题描述

var hello = "hello, how are you?"

var hello2 = "hello, how are you @tom?"

我想删除@符号后面的每个字母。

i want to delete every letter behind the @ sign.

结果应该是

var hello2 = "hello, how are you @tom?"
->
hello2.trimmed() 

print(hello2.trimmed())

-> "hello, how are you"

更新
想要使用它链接多个用户并用正确的名称替换@sign后面的空格，我总是需要引用最新出现的@sign来替换它。

Update As i want to use it to link multiple users and replace the space behind @sign with the correct name, I always need the reference to the latest occurrence of the @sign to replace it.

text3 = "hey i love you @Tom @Marcus @Peter"

示例最终版本应该是什么样子

Example what the final version should look like

开始

var text = hello @tom @mark @mathias

var text = "hello @tom @mark @mathias"

我想始终获取文本中最新@符号的索引

i want to always get the index of the latest @ sign in the text

推荐答案

在@appzYourLife答案上进行扩展，在删除@符号后的所有内容后，以下内容也将修剪空白字符。

Expanding on @appzYourLife answer, the following will also trim off the whitespace characters after removing everything after the @ symbol.

import Foundation

var str = "hello, how are you @tom"

if str.contains("@") {
    let endIndex = str.range(of: "@")!.lowerBound
    str = str.substring(to: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)
}
print(str) // Output - "hello, how are you"

更新：

为响应 @的最后一次出现删除字符串中的符号，这是我的处理方法：

In response to finding the last occurance of the @ symbol in the string and removing it, here is how I would approach it:

var str = "hello, how are you @tom @tim?"
if str.contains("@") {
    //Reverse the string
    var reversedStr = String(str.characters.reversed())
    //Find the first (last) occurance of @
    let endIndex = reversedStr.range(of: "@")!.upperBound
    //Get the string up to and after the @ symbol
    let newStr = reversedStr.substring(from: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)

    //Store the new string over the original
    str = String(newStr.characters.reversed())
    //str = "hello, how are you @tom"
}

在@appzYourLife答案中使用 range（of：options：range：locale：）而不是从字面上反转字符

Or looking at @appzYourLife answer use range(of:options:range:locale:) instead of literally reversing the characters

var str = "hello, how are you @tom @tim?"
if str.contains("@") {
    //Find the last occurrence of @
    let endIndex = str.range(of: "@", options: .backwards, range: nil, locale: nil)!.lowerBound
    //Get the string up to and after the @ symbol
    let newStr = str.substring(from: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)

    //Store the new string over the original
    str = newStr
    //str = "hello, how are you @tom"
}

作为额外的奖励，这是我将删除每个 @ 的方式从最后一个开始，然后向前进行：

As an added bonus, here is how I would approach removing every @ starting with the last and working forward:

var str = "hello, how are you @tom and @tim?"
if str.contains("@") {

    while str.contains("@") {
        //Reverse the string
        var reversedStr = String(str.characters.reversed())
        //Find the first (last) occurance of @
        let endIndex = reversedStr.range(of: "@")!.upperBound
        //Get the string up to and after the @ symbol
        let newStr = reversedStr.substring(from: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)

        //Store the new string over the original
        str = String(newStr.characters.reversed())
    }
    //after while loop, str = "hello, how are you"
}

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