An NSFormatter subclass written in Swift for converting strings to uppercase.

UppercaseFormatter.swift

import Foundation

class UppercaseFormatter : Formatter {
    
    override func string(for obj: Any?) -> String? {
        if let stringValue = obj as? String {
            return stringValue.uppercased()
        }
        return nil
    }
    
    override func getObjectValue(_ obj: AutoreleasingUnsafeMutablePointer<AnyObject?>?, for string: String, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
        obj?.pointee = string as AnyObject
        return true
    }
}