Delete all characters after a certain character from a string in Swift

You could do it like this:

guard let range = text.rangeOfString("Your String or Character here") else {
    return the text 
}

return text.substringToIndex(range.endIndex)
// depending on if you want to delete before a certain string, you would use range.startIndex

You can use StringProtocol method range(of string:), get the resulting range lowerBound, create a PartialRangeUpTo with it and subscript the original string:

Swift 4 or later

let word = "orange"
if let index = word.range(of: "n")?.lowerBound {
    let substring = word[..<index]                 // "ora"
    // or  let substring = word.prefix(upTo: index) // "ora"
    // (see picture below) Using the prefix(upTo:) method is equivalent to using a partial half-open range as the collection’s subscript. 
    // The subscript notation is preferred over prefix(upTo:).

    let string = String(substring)
    print(string)  // "ora"
}