手撸一个Flutter插件实现跨苹果全家桶云同步持久化Key Value数据

2,617 阅读4分钟

前言

作为一个客户端开发者,后端开发一直是我的弱项。虽然GPT的横空出世,让我对后端的开发有一点眉目。但是现实是,能不触碰就不触碰,因为人的精力是有限,如何在有限的时间里发挥最大的作用一直是我的一个追求。所以回到本次主题,我自己上线的一个产品,目前已经成功上线了iOS以及Mac端,如何在不开发后端的情况下实现同步轻量级数据呢?答案是利用Cloud Kit。Cloud Kit是苹果官方API,用于同步同一iCloud账号下设备的数据,包括Key Value Storage、云dataBase、云document等等。通过翻阅pub类似的库,我发现了有以下几个pub包是可以参考的cloud_kiticloud_storage,但是他们都不是我想要的,要么是不支持Mac、要么是只能同步存储文件,但是我想要同步的其实只是轻量级持久化数据(也是就是iOS下的UserDefault,基于键值存储)。所以没办法了,肝了一晚上我手撸了一个Flutter插件icloud_kv_storage,完美的支持了跨苹果设备iOS、Mac、iPad等的轻量级Key Value数据同步。

64556c9d-397f-4ef2-b615-1eebfd972592.gif

开发过程全解析

  • 创建Flutter插件项目,指定支持iOS、Mac平台

如何创建插件虽然已经很简单,这里我还是点一下。


flutter create icloud_kv_storage -t plugin

cd ./icloud_kv_storage

//指定platforms

flutter create ./ -t plugin --platforms ios

flutter create ./ -t plugin --platforms macos

  • 先设计Flutter Channel接口

由于是肝了一晚上的产品,非常赶,第一版先只支持同步String数据,后续再支持别的基础数据,如int、double、bool等。


///获取真正的Key,我内部Key都加了flutter前缀,如果要拿真实的Key可以使用此方法

String getRealKey(String key) {

throw UnimplementedError('getRealKey()) has not been implemented.');

}

///原生的CallBack 用于实时刷新数据(如果多台苹果设备都在线,支持实时同步

void setNativeCallBack({required GetNativeCallBackFuture onCallBack}) {

}

///保存数据接口,这里用范型方便后续拓展,虽然第一版只支持String

Future<void> write<T>({required String key,required T value}) {

throw UnimplementedError('write({required String key,required String value}) has not been implemented.');

}

///读取一个Key的数据接口,同理也是范型

Future<T?> read<T>({required String key}) {

throw UnimplementedError('read({required String key}) has not been implemented.');

}

///删除一个key

Future<void> delete({required String key}) {

throw UnimplementedError('delete({required String key}) has not been implemented.');

}

  • 原生Swift接口的实现

iOS和Mac实际都是共用Foundation框架,所以我们只需要编写同一套Swift实现,即可同时满足iOS以及Mac。

1.首先定义Channel实现协议


enum CKCommandType: String {

case DELETE_VALUE

case GET_VALUE

case SAVE_VALUE

case EMPTY = ""

}

protocol CKCommandHandlerProtocol {

var COMMAND_NAME: CKCommandType { get }

func evaluateExecution(command: String) -> Bool

func handle(command: String, arguments: Dictionary<String, Any>, result: @escaping FlutterResult) -> Void

}

2.实现增删改查对应methodName的协议

查询一个key对应的协议实现


class CKGetValueHandler: CKCommandHandlerProtocol {

var COMMAND_NAME: CKCommandType = .GET_VALUE

func evaluateExecution(command: String) -> Bool {

return CKCommandType(rawValue: command) == COMMAND_NAME

}

func handle(command: String, arguments: Dictionary<String, Any>, result: @escaping FlutterResult) {

if (!evaluateExecution(command: command)) {

return

}

if let key = arguments["key"] as? String {

let store = NSUbiquitousKeyValueStore.default

result(store.object(forKey: key))

} else {

result(FlutterError.init(code: "Error", message: "Cannot pass key and value parameter", details: nil))

}

}

}

删除一个Key的实现


class CKDeleteValueHandler: CKCommandHandlerProtocol {

var COMMAND_NAME: CKCommandType = .DELETE_VALUE

func evaluateExecution(command: String) -> Bool {

return CKCommandType(rawValue: command) == COMMAND_NAME

}

func handle(command: String, arguments: Dictionary<String, Any>, result: @escaping FlutterResult) {

if (!evaluateExecution(command: command)) {

return

}

if let key = arguments["key"] as? String {

let store = NSUbiquitousKeyValueStore.default

store.removeObject(forKey: key)

result(true)

} else {

result(FlutterError.init(code: "Error", message: "Cannot pass key parameter", details: nil))

}

}

}

写入保存一个Key的实现


class CKSaveValueHandler: CKCommandHandlerProtocol {

var COMMAND_NAME: CKCommandType = .SAVE_VALUE

func evaluateExecution(command: String) -> Bool {

return CKCommandType(rawValue: command) == COMMAND_NAME

}

func handle(command: String, arguments: Dictionary<String, Any>, result: @escaping FlutterResult) {

if (!evaluateExecution(command: command)) {

return

}

if let key = arguments["key"] as? String, let value = arguments["value"] as? String{

let store = NSUbiquitousKeyValueStore.default

store.set(value, forKey: key)

result(true)

} else {

result(FlutterError.init(code: "Error", message: "Cannot pass key and value parameter", details: nil))

}

}

}

  • 多设备实时刷新的实现

这里其实实现一下原生的通知监听,返回到Flutter就行,代码如下。


let keyValueStore = NSUbiquitousKeyValueStore.default

// 监听数据变化

NotificationCenter.default.addObserver(self, selector: #selector(keyValueStoreDidChange), name: NSUbiquitousKeyValueStore.didChangeExternallyNotification, object: keyValueStore)

keyValueStore.synchronize()

@objc func keyValueStoreDidChange(notification: Notification) {

// 处理数据变化

if let userInfo = notification.userInfo as? [String: Any],

let reasonForChange = userInfo[NSUbiquitousKeyValueStoreChangeReasonKey] as? NSNumber {

var reason = -1

reason = reasonForChange.intValue

if (reason == NSUbiquitousKeyValueStoreServerChange || reason == NSUbiquitousKeyValueStoreInitialSyncChange) {

guard let changedKeys = userInfo[NSUbiquitousKeyValueStoreChangedKeysKey] as? [String] else {

return

}

let store = NSUbiquitousKeyValueStore.default

for key in changedKeys {

let value = store.object(forKey: key)

self.channel?.invokeMethod("icloud_key_update", arguments: [key:value])

}

}

}

}

  • Plugin Channel通讯的处理

上面一个一个的协议实现完毕,我们只需要扔到Flutter Plugin handle的协议方法里就可。代码如下


public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {

let callArguments: Dictionary<String, Any> = call.arguments as! Dictionary<String, Any>

CKGetValueHandler().handle(command: call.method, arguments: callArguments, result: result)

CKSaveValueHandler().handle(command: call.method, arguments: callArguments, result: result)

CKDeleteValueHandler().handle(command: call.method, arguments: callArguments, result: result)

}

就这样一个支持跨苹果全家桶同步持久化Key Value数据的Flutter插件就完全了,是不是很简单呢?

用法

首先我们要在iOS或Mac项目开启iCloud Key Value Storge 服务

Snip20230607_3.png

然后导入icloud_kv_storage享受它吧~


flutter pub add icloud_kv_storage

dependencies:

icloud_kv_storage: ^0.0.1

简单写法如下


import 'package:icloud_kv_storage/icloud_kv_storage.dart';

var iCloudStorage = CKKVStorage();

Update A Key


void _incrementCounter() {

setState(() {

_counter++;

iCloudStorage.writeString(key: key, value: _counter.toString());

});

}

Read A Key


iCloudStorage.getString('k_storage_count').then((value) {

if (value != null) {

setState(() {

_counter = int.parse(value);

});

}

});

Delete A Key


void _clearCounter() {

setState(() {

_counter = 0;

iCloudStorage.delete(key);

});

}

实时刷新CallBack


iCloudStorage.onCloudKitKVUpdateCallBack(

onCallBack: (kvMap) {

print('receive icloud_key_update map $kvMap');

//if receive remove key will rec {flutter.k_storage_count: null}

//if receive update key will rec {flutter.k_storage_count: 1}

//because have prefix flutter. so need use my method to get real key.

var key = iCloudStorage.getRealKey('k_storage_count');

if (kvMap.containsKey(key)) {

String? value = kvMap[key];

setState(() {

if (value != null) {

_counter =

int.parse(kvMap[iCloudStorage.getRealKey('k_storage_count')]);

} else {

_counter = 0;

}

});

}

},

);

下载地址

Github

icloud_kv_storage

flutter pub

icloud_kv_storage

结尾

由于是1.0版本,非常肝。目前只支持同步String类型的数据,后续其他基础类型数据也会更新上。如果这个库对你有用,那就Star一个吧,感谢🙏