在 apple iWatch 中，后台任务未被调用或按计划时间触发

Question

当应用程序在后台触发任务时更新位置。但无法以后台模式执行任务。我的 scheduleBackgroundRefreshWithPreferredDate 示例代码如下

[WKExtension.sharedExtension scheduleBackgroundRefreshWithPreferredDate:[NSDate dateWithTimeIntervalSinceNow:60] userInfo:nil scheduledCompletion:^(NSError * _Nullable error) {

        if(error == nil) {
            NSLog(@"background refresh task re-scheduling successfuly  ");

        } else{

            NSLog(@"Error occurred while re-scheduling background refresh: %@",error.localizedDescription);
        }
    }];

在 handleBackgroundTasks:

中安排任务重新安排

- (void)handleBackgroundTasks:(NSSet<WKRefreshBackgroundTask *> *)backgroundTasks
{
    for (WKRefreshBackgroundTask * task in backgroundTasks) {

        if ([task isKindOfClass:[WKApplicationRefreshBackgroundTask class]]) {
            WKApplicationRefreshBackgroundTask *backgroundTask = (WKApplicationRefreshBackgroundTask*)task;
            // location update methods schedule as background task
            [self startLocationUpdate];
            [backgroundTask setTaskCompleted];

        } else if ([task isKindOfClass:[WKSnapshotRefreshBackgroundTask class]]) {
            WKSnapshotRefreshBackgroundTask *snapshotTask = (WKSnapshotRefreshBackgroundTask*)task;
            [snapshotTask setTaskCompletedWithDefaultStateRestored:YES estimatedSnapshotExpiration:[NSDate distantFuture] userInfo:nil];

        } else if ([task isKindOfClass:[WKWatchConnectivityRefreshBackgroundTask class]]) {
            WKWatchConnectivityRefreshBackgroundTask *backgroundTask = (WKWatchConnectivityRefreshBackgroundTask*)task;
            [backgroundTask setTaskCompleted];

        } else if ([task isKindOfClass:[WKURLSessionRefreshBackgroundTask class]]) {
            WKURLSessionRefreshBackgroundTask *backgroundTask = (WKURLSessionRefreshBackgroundTask*)task;
            [backgroundTask setTaskCompleted];

        } else {
            [task setTaskCompleted];
        }
    }
}

后台任务方法如下

-(void)startLocationUpdate {

    locationMgr = [[CLLocationManager alloc] init];
    [locationMgr setDelegate:self];

    locationMgr.desiredAccuracy = kCLLocationAccuracyBest;
    locationMgr.distanceFilter = kCLDistanceFilterNone;

    //    locationMgr.allowsBackgroundLocationUpdates = YES;

    [locationMgr requestAlwaysAuthorization];
    [locationMgr startUpdatingLocation];

    [WKExtension.sharedExtension scheduleBackgroundRefreshWithPreferredDate:[NSDate dateWithTimeIntervalSinceNow:60] userInfo:nil scheduledCompletion:^(NSError * _Nullable error) {

        if(error == nil) {
            NSLog(@"background refresh task re-scheduling successfuly  ");

        } else{

            NSLog(@"Error occurred while re-scheduling background refresh: %@",error.localizedDescription);
        }
    }];

}
- (void)locationManager:(CLLocationManager *)manager
     didUpdateLocations:(NSArray<CLLocation *> *)locations {

    NSTimeInterval locationAge = -[[locations lastObject].timestamp timeIntervalSinceNow];

    NSLog(@"Location Age : %f",locationAge);

    if (locationAge > 5.0) return;

    NSLog(@"latitude: %f longitude: %f",[locations lastObject].coordinate.latitude,[locations lastObject].coordinate.longitude);

    //NSString *strLocation = [NSString stringWithFormat:@"%f,%f" ,[locations lastObject].coordinate.latitude , [locations lastObject].coordinate.longitude];
    NSString *strLocation = @"bgLocation";

    NSDictionary *applicationData = [[NSDictionary alloc] initWithObjects:@[strLocation] forKeys:@[@"watchlocation"]];

   [[WCSession defaultSession] transferUserInfo:applicationData];

}

Answer 1

后台执行在 watchOS3 上非常困难。有很多限制，即使您成功安排了后台刷新任务，也不能保证 watchOS 会启动它。

根据我深入研究 WWDC 会议和文档后的经验：

如果应用程序不在 Dock 中或当前表盘上没有活动的复杂功能，watchOS3 将不会为您的应用程序提供任何后台执行时间
Dock 中的应用程序的后台刷新任务数量限制为每小时 1 次，具有活动并发症的应用程序每小时 2 次
后台执行时间也有限制，如果app超过这个时间，会被watchOS daemon终止
一旦您调用 setTaskCompleted，应用程序将进入挂起状态，因此不应执行代码中的异步 locationManager:didUpdateLocations: 方法

在 apple iWatch 中，后台任务未被调用或按计划时间触发

In apple iWatch background task is not getting called or triggering with schedule time

objective-c

ios

watchkit

watchos-3

watchos-4