Apple Watch 和 iPhone 同步, 表盘开发

iPhone 端同步

remainingComplicationUserInfoTransfers

//If the complication is on the active watch face, you are given 50 transfers a day. If the complication is not active, this property defaults to 0.

iPhone 每天可以唤醒 Watch 50 次, WCSession.default.remainingComplicationUserInfoTransfers, 可以直接知道当前剩余次数, 如果使用者在 iPhone 上关闭了复杂功能, 那直接返回0, 如果剩余次数为零的时候, 就会使用transferUserInfo(_:), 替换transferCurrentComplicationUserInfo(_:), transferUserInfo(_:) 只有当 watch app 进入前台之后才会唤醒, 官方说会在适当的时机唤醒, 肯定是不会立即唤醒.

Watch 端接收

//The background watch connectivity task informs you that your app has been given background time. You must use your [WCSessionDelegate](https://developer.apple.com/documentation/watchconnectivity/wcsessiondelegate) methods to receive this data. Because of the asynchronous nature of these tasks, you must defer calling your tasks’s `Completed()` method until after you have activated your session and received all the pending data. Use the `hasContentPending` method to determine whether you still have any pending data.

Watch 在后台收到 iPhone 推送数据的时候, 会先在 handle 方法中返回一个 WKWatchConnectivityRefreshBackgroundTask 后台任务, 如果这个任务 Completed(), Watch 将会挂起, 所以在这之前一定要保证所有的同步完成.

表盘数据更新

只说一下 getCurrentTimelineEntry 方法, 这个方法是为表盘提供数据的,
表盘控件有不同模板, 需要提供不同的数据, 这里就不一一介绍可以参阅CLKComplicationTemplate, 主要说一下更新表盘数据, 每次获取新数据, 都需要 reloadTimeline, 这样就会从新走 getCurrentTimelineEntry 回调方法.

            let server = CLKComplicationServer.sharedInstance()
            for complication in server.activeComplications ?? [] {
                server.reloadTimeline(for: complication)
            }

这里最大的问题就是每天只能唤醒50次, 超过50次, 就没法立即唤醒 APP, 那么就没法及时更新表盘数据.