关于 Realm 数据库

// Define your models like regular Swift classes
class Dog: Object {
    @Persisted var name: String
    @Persisted var age: Int
}
class Person: Object {
    @Persisted(primaryKey: true) var _id: String
    @Persisted var name: String
    @Persisted var age: Int
    // Create relationships by pointing an Object field to another Class
    @Persisted var dogs: List<Dog>
}
// Use them like regular Swift objects
let dog = Dog()
dog.name = "Rex"
dog.age = 1
print("name of dog: \(dog.name)")

// Get the default Realm
let realm = try! Realm()
// Persist your data easily with a write transaction
try! realm.write {
    realm.add(dog)
}

// Open the default realm.
let realm = try! Realm()

var token: NotificationToken?

let dog = Dog()
dog.name = "Max"

// Create a dog in the realm.
try! realm.write {
    realm.add(dog)
}

//  Set up the listener & observe object notifications.
token = dog.observe { change in
    switch change {
    case .change(let properties):
        for property in properties {
            print("Property '\(property.name)' changed to '\(property.newValue!)'");
        }
    case .error(let error):
        print("An error occurred: (error)")
    case .deleted:
        print("The object was deleted.")
    }
}

// Update the dog's name to see the effect.
try! realm.write {
    dog.name = "Wolfie"
}

struct ContactsView: View {
    @ObservedResults(Person.self) var persons

    var body: some View {
        List {
            ForEach(persons) { person in
                Text(person.name)
            }
            .onMove(perform: $persons.move)
            .onDelete(perform: $persons.remove)
        }.navigationBarItems(trailing:
            Button("Add") {
                $persons.append(Person())
            }
        )
    }
}

// Generate a random encryption key
var key = Data(count: 64)
_ = key.withUnsafeMutableBytes { (pointer: UnsafeMutableRawBufferPointer) in
    guard let baseAddress = pointer.baseAddress else {
        fatalError("Failed to obtain base address")
    }
    SecRandomCopyBytes(kSecRandomDefault, 64, baseAddress)
}

// Add the encryption key to the config and open the realm
let config = Realm.Configuration(encryptionKey: key)
let realm = try Realm(configuration: config)

// Use the Realm as normal
let dogs = realm.objects(Dog.self).filter("name contains 'Fido'")