ios - Swift 使用 realm.add() 或 realm.create() 将大量数据写入 Realm

Question

我需要向 Realm 写入大量数据(例如 200000 输入)，我使用 realm.add() 在后台线程中写入数据。但它收到了崩溃消息:

Terminating app due to uncaught exception 'RLMException', reason: 'Realm accessed from incorrect thread.'

let cities = try decoder.decode([City].self, from: dataFromStream)
let dispatchQueue = DispatchQueue(label: "com.example.myApp.bg", qos: .background)
dispatchQueue.async {
    let myBackgroundRealm = try! Realm()
    myBackgroundRealm.beginWrite()

    for city in cities {
        myBackgroundRealm.add(city, update: false)
    }

    try! myBackgroundRealm.commitWrite()
}

所以我改为使用 Realm.create()，它起作用了。但是我仍然不明白 Realm.create() 和 Realm.add() 在写入大数据时有什么区别。

let cities = try decoder.decode([City].self, from: data)
let dispatchQueue = DispatchQueue(label: "com.example.myApp.bg", qos: .background)
dispatchQueue.async {
    let myBackgroundRealm = try! Realm()

    for city in cities {
        try! myBackgroundRealm.write {
            myBackgroundRealm.create(City.self, value: city, update: false)
        }
    }
}

Answer 1

当对 Realm 进行异步写入时，您必须初始化线程安全引用并在后台线程中解析该引用。取自 Realm 的文档 https://realm.io/docs/swift/latest/#passing-instances-across-threads

let person = Person(name: "Jane")
try! realm.write {
    realm.add(person)
}
let personRef = ThreadSafeReference(to: person)
DispatchQueue(label: "background").async {
    autoreleasepool {
        let realm = try! Realm()
        guard let person = realm.resolve(personRef) else {
            return // person was deleted
        }
        try! realm.write {
            person.name = "Jane Doe"
        }
    }
}