What am I missing in my random lowercase string generator function ? Using Swift 5.5 [duplicate]

I have a function I use to generate random strings for email addresses or passwords (for example). It was originally set like this:

static func random(length: Int) -> String {
let characters = "abcdefghijklmnopqrstuvwxyz"
return String((0..<length).map { _ in characters.randomElement()! })
}

So I changed it to this:

static func random(length: Int) -> String {
let characters = CharacterSet.lowercaseLetters
return String((0..<length).map { _ in characters.randomElement()! })
}

But I get an error saying "Value of type 'CharacterSet' has no member 'randomElement'.

I'm very new to Swift and I've done a lot of searching and so far I haven't found a good solution. I want to keep this function short and sweet. And I've been at this for a while now. Any help would be greatly appreciated! Please let me know if any more context is needed.

Edit: My question got closed because it was seen as a duplicate but, I looked at the solution page and tried to apply it to my issue and still no resolution. I'm not sure if that's because the previous answers are from 2015 and older or they were for obj-c