Question

我对NSNotification感到沮丧。不知怎的，我的视图控制器无法接收回调。我在互联网上浏览过但没有找到任何解决方案。这是我的代码

SideBarViewController.h

- (void)postNotificationWithString:(NSString *)deviceLocation {

    NSString *notificationName = @"LocationDetectedNotification";

    NSDictionary *dict = [NSDictionary dictionaryWithObject:deviceLocation forKey:@"MyLocation"];

    [[NSNotificationCenter defaultCenter] postNotificationName:notificationName object:nil userInfo:dict];

}

- (void)locationManager:(CLLocationManager *)manager
 didUpdateLocations:(NSArray *)locations {

CLLocation *currentLocation = [locations lastObject];

if (currentLocation != nil) {
  lon = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.longitude];
  lat = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude];
  [self postNotificationWithString:[NSString stringWithFormat:@"%@,%@", lat, lon]];

}
// Save battery consumption
[locationManager stopUpdatingLocation];
}

TestViewController.h

@implementation TestViewController

- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
    // Custom initialization


}
return self;
}

- (void)viewDidLoad {

     [[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(useNotificationWithString:) name:@"LocationDetectedNotification" object:nil];

{
- (void)useNotificationWithString:(NSNotification*)notification {
    NSLog(@"Location Retrieved");
    NSDictionary *dict = [notification userInfo];
    self.location = [dict valueForKey:@"MyLocation"];

}

当我点击TestViewController时，什么也没发生。我使用storyboard来创建视图控制器。提前谢谢！

Answer 1

我认为您的问题是您在第一个视图控制器的[locationManager startUpdatingLocation]方法中执行viewDidLoad，然后在[locationManager stopUpdatingLocation]方法中执行- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations。

我的猜测是，您收到了该位置，并且在实例化TestViewController之前停止了位置管理器，这意味着尚未注册观察者。

ViewController未收到NSNotification

1 个答案: