use a propertyWrapper for keychain in SwiftUI

KeyChainHelper.swift

import Foundation

class KeyChainHelper {
    
    static let shared = KeyChainHelper()
    
    func save(data: Data, key: String, account: String) {
        
        let query = [
            kSecValueData: data,
            kSecAttrAccount: account,
            kSecAttrService: key,
            kSecClass: kSecClassGenericPassword
        ] as CFDictionary
        
        let status = SecItemAdd(query, nil)
        
        switch status {
        case errSecSuccess: print("success")
        case errSecDuplicateItem:
            let query = [
                kSecValueData: data,
                kSecAttrAccount: account,
                kSecAttrService: key,
                kSecClass: kSecClassGenericPassword
            ] as CFDictionary
            
            let updateAttr = [kSecValueData: data] as CFDictionary
            
            SecItemUpdate(query, updateAttr)
            
        default: print("Error \(status)")
        }
    }
    
    func read(key: String, account: String) -> Data? {
        
        let query = [
            kSecAttrAccount: account,
            kSecAttrService: key,
            kSecClass: kSecClassGenericPassword,
            kSecReturnData: true
        ] as CFDictionary
        
        var resultData: AnyObject?
        
        SecItemCopyMatching(query, &resultData)
        
        return resultData as? Data
    }
    
    func delete(key: String, account: String) {
        
        let query = [
            kSecAttrAccount: account,
            kSecAttrService: key,
            kSecClass: kSecClassGenericPassword,
        ] as CFDictionary
        
        SecItemDelete(query)
    }
}

KeyChainPropertyWrapper.swift

import SwiftUI

@propertyWrapper
struct KeyChainPropertyWrapper: DynamicProperty {
    
    @State var data: Data?
    
    var wrappedValue: Data? {
        get {
            data
        }
        nonmutating set {
            
            guard let newValue = newValue else {
                
                data = nil
                KeyChainHelper.shared.delete(key: key, account: account)
                return
            }
            
            KeyChainHelper.shared.save(data: newValue, key: key, account: account)
            
            data = newValue
        }
    }
    
    var key: String
    var account: String
    
    init(key: String, account: String) {
        self.key = key
        self.account = account
        
        _data = State(wrappedValue: KeyChainHelper.shared.read(key: key, account: account))
    }
}

KeyChainView.swift

import SwiftUI

struct KeyChainView: View {
    
    @KeyChainPropertyWrapper(key: "text", account: "keychainview") var textData
    
    @State var inputText: String = ""
    
    var body: some View {
        
        VStack {
            HStack {
                TextField("input", text: $inputText)
                    .padding()
                    .background(.thinMaterial)
                    .cornerRadius(10)
                Button("save") {
                    let textData = inputText.data(using: .utf8)
                    self.textData = textData
                }
            }
            .padding(.horizontal)
            
            HStack(spacing: 0) {
                Text("Saved Text : ")
                
                if let textData = textData {
                    Text(String(data: textData, encoding: .utf8) ?? "no saved text")
                }
            }
            .padding()
        }
    }
}


struct KeyChainView_Previews: PreviewProvider {
    static var previews: some View {
        KeyChainView()
    }
}

https://youtu.be/HvT0PAKM0LI