我最终解决了自己的问题。

显然，在iOS 8 SDK中，在开始位置更新之前需要调用CLLocationManager上的requestAlwaysAuthorization(用于后台位置)或requestWhenInUseAuthorization(仅用于前台位置)。

在Info中还需要NSLocationAlwaysUsageDescription或NSLocationWhenInUseUsageDescription键。Plist并在提示符中显示一条消息。加上这些就解决了我的问题。

更多详细信息，请查看:Core-Location-Manager-Changes-in-ios-8

我的解决方案可以在Xcode 5中编译:

#ifdef __IPHONE_8_0
    NSUInteger code = [CLLocationManager authorizationStatus];
    if (code == kCLAuthorizationStatusNotDetermined && ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)] || [self.locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)])) {
        // choose one request according to your business.
        if([[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSLocationAlwaysUsageDescription"]){
            [self.locationManager requestAlwaysAuthorization];
        } else if([[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSLocationWhenInUseUsageDescription"]) {
            [self.locationManager  requestWhenInUseAuthorization];
        } else {
            NSLog(@"Info.plist does not contain NSLocationAlwaysUsageDescription or NSLocationWhenInUseUsageDescription");
        }
    }
#endif
    [self.locationManager startUpdatingLocation];

解决方案与向后兼容，不产生Xcode警告:

SEL requestSelector = NSSelectorFromString(@"requestWhenInUseAuthorization");
if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusNotDetermined &&
  [self.locationManager respondsToSelector:requestSelector]) {
((void (*)(id, SEL))[self.locationManager methodForSelector:requestSelector])(self.locationManager, requestSelector);
  [self.locationManager startUpdatingLocation];
} else {
  [self.locationManager startUpdatingLocation];
}

在Info.plist中设置NSLocationWhenInUseUsageDescription键。

对于iOS版本11.0+: 在Info.plist中设置NSLocationAlwaysAndWhenInUseUsageDescription键。还有另外2把钥匙。

用于询问位置的旧代码将无法在iOS 8中使用。您可以尝试使用此方法进行位置授权:

- (void)requestAlwaysAuthorization
{
    CLAuthorizationStatus status = [CLLocationManager authorizationStatus];

    // If the status is denied or only granted for when in use, display an alert
    if (status == kCLAuthorizationStatusAuthorizedWhenInUse || status ==        kCLAuthorizationStatusDenied) {
        NSString *title;
        title = (status == kCLAuthorizationStatusDenied) ? @"Location services are off" :   @"Background location is not enabled";
        NSString *message = @"To use background location you must turn on 'Always' in the Location Services Settings";

        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title
                                                            message:message
                                                           delegate:self
                                                  cancelButtonTitle:@"Cancel"
                                                  otherButtonTitles:@"Settings", nil];
        [alertView show];
    }
    // The user has not enabled any location services. Request background authorization.
    else if (status == kCLAuthorizationStatusNotDetermined) {
        [self.locationManager requestAlwaysAuthorization];
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 1) {
        // Send the user to the Settings for this app
        NSURL *settingsURL = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
        [[UIApplication sharedApplication] openURL:settingsURL];
    }
}

对于那些使用Xamarin，我必须添加关键NSLocationWhenInUseUsageDescription的信息。手动plist，因为在Xamarin 5.5.3 Build 6或XCode 6.1的下拉列表中都不可用-只有NSLocationUsageDescription在列表中，这导致CLLocationManager继续无声地失败。

要在iOS 8中访问用户位置，你必须添加，

NSLocationAlwaysUsageDescription in the Info.plist 

这将询问用户获取其当前位置的权限。