ios - Realm 更新数据 + DispatchQueue

Question

我在后台更新数据库。我的数据可能包含约 2000 项，更新需要时间。

func updateData(items: [JSON], _ complete:@escaping() -> Void) {
    DispatchQueue.global(qos: .userInitiated).async {

       let currentModels = EgrnModel.getAllModels()
       var newModels: [EgrnModel] = []
       var toDelete: [EgrnModel] = []

       for model in currentModels {
           let contain = items.contains(where: {$0["id"].intValue == model.id})
           if !contain {
               toDelete.append(model)
           }
       }


       let realm = try! Realm()
       try! realm.write {
           for item in items {
               if let model = currentModels.first(where: {$0.id == item["id"].intValue}) {
                   model.update(item)
               }
               else {
                   newModels.append(EgrnModel(item))
               }
           }
           realm.delete(toDelete)
           realm.add(newModels)
       }

       DispatchQueue.main.async {
           complete()
       }
    }
}

我有一个函数，我需要在其中立即更新数据。当我点击复选标记时，我卡住了。 (我认为是因为此时其他数据正在后台更新)

---

func checkMark(index: Int) {

    let model = models[index]
    let realm = try! Realm()

    try! realm.write {
        model.needToUpdateOnServer = true
        model.lastEditUpdate = Date()
        model.read = true
    }
}

我尝试下一个代码来修复卡住。但是在这段代码中，我遇到了一个崩溃 Termating app due to uncaught exception 'RLMException', reason: 'Realm accessed from incorrect thread.

func checkMark(index: Int) {

    let model = models[index]

    DispatchQueue.global(qos: .userInitiated).async {

        let realm = try! Realm()

        try! realm.write {
            model.needToUpdateOnServer = true
            model.lastEditUpdate = Date()
            model.read = true
        }
    }
}

Answer 1

您需要做的是将 Realm 对象从一个线程“移动”到另一个线程，因为 Realm 对象不是线程安全的，而是线程受限的。为此，您必须使用 ThreadSafeReference API。

要解决此问题，请执行以下操作:

1. 在 Realm 类上创建扩展

extension Realm {
    func writeAsync<T : ThreadConfined>(obj: T, errorHandler: @escaping ((_ error : Swift.Error) -> Void) = { _ in return }, block: @escaping ((Realm, T?) -> Void)) {
        let wrappedObj = ThreadSafeReference(to: obj)
        let config = self.configuration
        DispatchQueue(label: "background").async {
            autoreleasepool {
                do {
                    let realm = try Realm(configuration: config)
                    let obj = realm.resolve(wrappedObj)

                    try realm.write {
                        block(realm, obj)
                    }
                }
                catch {
                    errorHandler(error)
                }
            }
        }
    }
}

1. 以这种方式在您的代码中使用它

func checkMark(index: Int) {

    let model = models[index]
    let realm = try! Realm()

    realm.asyncWrite(model) { realm, model in
        model.needToUpdateOnServer = true
        model.lastEditUpdate = Date()
        model.read = true
    }
}

祝您刷卡愉快!