【发布时间】：2012-09-03 19:59:36
【问题描述】：
如果应用程序正在运行并且 CLLocationManagerDelegate 类是前台（即可见），则 didEnterRegions 触发并且我得到 NSLog 和 AlertView。但是，当应用程序在后台时，或者基本上，如果屏幕显示的不是委托类，我什么也得不到。
我已经在 plist 中的“必需的后台模式”下设置了“应用程序注册以进行位置更新”，尽管我不确定这是否有必要。
这就是我认为的相关代码，尽管我可能是错的（并且很乐意添加更多）。我应该注意 viewDidLoad 中的所有内容都包含在 if 中，它检查区域监控是否可用和启用。
- (void)viewDidLoad
{
NSLog(@"MapViewController - viewDidLoad");
self.locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
self.locationManager.distanceFilter = kCLLocationAccuracyNearestTenMeters;
self.locationManager.delegate = self;
[self.locationManager startMonitoringSignificantLocationChanges];
}
- (void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region
{
NSLog(@"MapViewController - didEnterRegion");
NSLog(@"MVC - didEnterRegion - region.radius = %f", region.radius);
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"entered region..." message:@"You have Entered the Location." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
alert.tag = 2;
[alert show];
}
这是我在 AppDelegate.m 中获得被监控区域列表的地方：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// other code
NSLog(@"LISTING ALL REGIONS MONITORED");
NSArray *regions = [self.locationManager.monitoredRegions allObjects];
if (!regions) {
NSLog(@"no regions found");
} else {
NSLog(@"got %d monitored regions", [regions count]);
for (int i = 0; i < [regions count]; i++) {
CLRegion *region = [regions objectAtIndex:i];
NSLog(@"region %d's identifier = %@", i, region.identifier);
NSLog(@"region: radius: %@", region.radius);
}
}
// other code
}
我调用 startMonitoringForRegion 两次，这里是主要的地方：
- (void)doneButtonTapped {
NSLog(@"doneButtonTapped");
if (self.locationIdentifier) {
if ([CLLocationManager regionMonitoringEnabled] && [CLLocationManager regionMonitoringAvailable]) {
// core data setup
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"LocationReminder" inManagedObjectContext:self.managedObjectContext];
fetchRequest.entity = entityDescription;
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"locationIdentifier == %@", self.locationIdentifier];
fetchRequest.predicate = predicate;
NSError *error;
NSArray *results = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (results) {
// get the LocationReminder
LocationReminder *retrievedReminder = [results objectAtIndex:0];
retrievedReminder.audioURI = [[[self.audioPlayers objectAtIndex:self.selectedCell] url] absoluteString];
retrievedReminder.userRecording = nil;
// start monitoring it's region
NSArray *coordinateArray = [retrievedReminder.locationIdentifier componentsSeparatedByString:@", "];
CLLocationCoordinate2D coordinate = {[[coordinateArray objectAtIndex:0] doubleValue], [[coordinateArray objectAtIndex:1] doubleValue]};
CLRegion *newRegion = [[CLRegion alloc] initCircularRegionWithCenter:coordinate radius:250.0 identifier:retrievedReminder.locationIdentifier];
NSLog(@"about to monitor region with radius: %f", newRegion.radius);
[self.locationManager startMonitoringForRegion:newRegion desiredAccuracy:kCLLocationAccuracyBest];
// save the LocationReminder
if (![self.managedObjectContext save:&error]) {
NSLog(@"hmm. no managed object context. must be something space-time going on");
} else {
NSLog(@"saved locationReminder, locationIdentifier = %@", retrievedReminder.locationIdentifier);
}
} else {
NSLog(@"ERROR: no LocationReminder retreived for predicate: %@", predicate);
}
}
// get the mapview controller off of the navigation stack
for (UIViewController *viewController in self.navigationController.viewControllers) {
if ([viewController isKindOfClass:[MapViewController class]]) {
MapViewController *mapVC = (MapViewController *)viewController;
mapVC.audioURI = [[[self.audioPlayers objectAtIndex:self.selectedCell] url] absoluteString];
[self.navigationController popToViewController:mapVC animated:YES];
}
}
}
因为我觉得它可能很重要，所以这里是 locationManager 的 getter：
- (CLLocationManager *)locationManager {
NSLog(@"MapViewController - locationManager");
if (_locationManager) {
return _locationManager;
} else {
_locationManager = [[CLLocationManager alloc] init];
return _locationManager;
}
}
更新 1： 通过 Apple 论坛（我在其中交叉发布）有人提到 AlertView 只会显示在前台。 NSLog 仍然没有触发。我假设这应该可行。
【问题讨论】：
-
能否在调用 startMonitoringForRegion 的位置包含代码？包含的代码现在没有显示，只会触发与重大位置更改相关的回调方法。根据我的经验，这些事件不会从模拟器中触发。
标签： ios cllocationmanager region-management clregion