iOS 钥匙串中的项目能否在应用程序卸载和重新安装后保留下来

iOS 钥匙串是一种安全的存储机制，用于保存敏感数据，如密码、证书、令牌等。在应用程序卸载和重新安装后，iOS 钥匙串中的项目是否能保留下来，取决于开发者在代码中的处理方式。

swift
// 保存数据
let serviceName = "com.example.app"
let account = "user@example.com"
let password = "123456"
let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: serviceName,
    kSecAttrAccount as String: account,
    kSecValueData as String: password.data(using: .utf8)!
]
let status = SecItemAdd(query as CFDictionary, nil)
if status == errSecSuccess {
    print("Data saved successfully")
} else {
    print("Failed to save data")
}
// 读取数据
let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: serviceName,
    kSecAttrAccount as String: account,
    kSecMatchLimit as String: kSecMatchLimitOne,
    kSecReturnData as String: true
]
var result: AnyObject?
let status = SecItemCopyMatching(query as CFDictionary, &result)
if status == errSecSuccess {
    if let data = result as? Data, let password = String(data: data, encoding: .utf8) {
        print("Password: \(password)")
    }
} else {
    print("Failed to read data")
}

swift
// 保存数据
let serviceName = "com.example.app"
let account = "user@example.com"
let password = "123456"
let accessGroup = "group.com.example.app"
let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: serviceName,
    kSecAttrAccount as String: account,
    kSecValueData as String: password.data(using: .utf8)!,
    kSecAttrAccessGroup as String: accessGroup
]
let status = SecItemAdd(query as CFDictionary, nil)
if status == errSecSuccess {
    print("Data saved successfully")
} else {
    print("Failed to save data")
}
// 读取数据
let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: serviceName,
    kSecAttrAccount as String: account,
    kSecAttrAccessGroup as String: accessGroup,
    kSecMatchLimit as String: kSecMatchLimitOne,
    kSecReturnData as String: true
]
var result: AnyObject?
let status = SecItemCopyMatching(query as CFDictionary, &result)
if status == errSecSuccess {
    if let data = result as? Data, let password = String(data: data, encoding: .utf8) {
        print("Password: \(password)")
    }
} else {
    print("Failed to read data")
}