Get the string up to a specific character

Question

var hello = \"hello, how are you?\"

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

i want to delete every letter behind the @ sign.

result shou

Answer 1

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"

UPDATE:

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"
}

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"
}

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"
}