Convert Swift strings to camel case

Camelizer.swift

fileprivate let badChars = CharacterSet.alphanumerics.inverted

extension String {
    var uppercasingFirst: String {
        return prefix(1).uppercased() + dropFirst()
    }

    var lowercasingFirst: String {
        return prefix(1).lowercased() + dropFirst()
    }

    var camelized: String {
        guard !isEmpty else {
            return ""
        }

        let parts = self.components(separatedBy: badChars)

        let first = String(describing: parts.first!).lowercasingFirst
        let rest = parts.dropFirst().map({String($0).uppercasingFirst})

        return ([first] + rest).joined(separator: "")
    }
}

Great work, thanks for sharing! I think the computation could be even faster if you move uppercasingFirst and lowercasingFirst into an extension of Substring. (There wouldn't even be a need to change their implementations.) Cheers.

A more compact version.

extension String {
    var lowercasingFirst: String { prefix(1).lowercased() + dropFirst() }
    var uppercasingFirst: String { prefix(1).uppercased() + dropFirst() }

    var camelCased: String {
        guard !isEmpty else { return "" }
        let parts = components(separatedBy: .alphanumerics.inverted)
        let first = parts.first!.lowercasingFirst
        let rest = parts.dropFirst().map { $0.uppercasingFirst }

        return ([first] + rest).joined()
    }
}

how did you come up with this? i am learning swift a while now and i am not gaining much knowledge.