Can you explain what is meant by the term KeyChain?.

Keychain in iOS is a secure storage for passwords, certificates, keys, and other confidential data. It provides safe storage and access to application-sensitive information.

Features of Keychain:

• Data is encrypted and stored in a protected area.
• Access to data is regulated by security policies and access rights.
• Allows storing information between app launches and even after deletion and reinstallation (if configured).

Example of using Keychain to save a password:

import Security

func savePassword(_ password: String, account: String) {
    let data = password.data(using: .utf8)!
    let query: [String: Any] = [
        kSecClass as String: kSecClassGenericPassword,
        kSecAttrAccount as String: account,
        kSecValueData as String: data
    ]
    SecItemAdd(query as CFDictionary, nil)
}

Thus, Keychain is the standard mechanism in iOS for securely storing secrets.