TextLimiter.swift

//
//  TextLimiter.swift
// 
//
//  Created by Sam Spencer on 2/1/22.
//

import Foundation
import SwiftUI

public class TextLimiter: ObservableObject {

    private let limit: Int
    
    public init(limit: Int) {
        self.limit = limit
    }
    
    @Published public var value = "" {
        didSet {
            if value.count > self.limit {
                value = String(value.prefix(self.limit))
                self.hasReachedLimit = true
             } else {
                 self.hasReachedLimit = false
             }
         }
     }
     
     @Published public var hasReachedLimit = false
     
}

/// Demo SwiftUI View
struct DemoView: View {

    @ObservedObject var password = TextLimiter(limit: 32)
    
    var body: some View {
        TextField("32 character password", text: $password.value)
            .padding()
    }
    
}

A semi-generic solution to validate a SwiftUI TextField's content as its changed, and make on-the-fly validation or changes to the value of the input.