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在我的 iphone 应用程序中，我正在使用 google places api - 在 mapView 上绘制附近的餐馆。我遇到的问题是当我在同一个 mapView 上处理核心数据对象时。澄清一下：用户可以选择一个图钉（餐厅）来加载该餐厅的详细信息屏幕（他们可以在其中保存评论、评级等）——然后我将该餐厅保存为核心数据对象。但是，下次加载 mapView 时，我不想显示来自 google api 搜索的普通 mapPoint 餐厅，而是显示保存的餐厅核心数据 mapPoint（针对该位置）。

以下是一些相关代码：

- (void)viewDidLoad
{
  [super viewDidLoad];

  locationManager = [[CLLocationManager alloc] init];
  [locationManager setDelegate:self];
  [locationManager setDistanceFilter:kCLDistanceFilterNone];
  [locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
  //[self updateRestaurants];

  NSEntityDescription *entity = [NSEntityDescription entityForName:@"Restaurant" inManagedObjectContext:self.managedObjectContext];
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
  [fetchRequest setEntity:entity];

  NSError *error;
  foundObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];

  //[self.mapView addAnnotations:foundObjects];

  [self performSelector:@selector(queryGooglePlaces) withObject:nil afterDelay:2.0];
}

- (void)updateRestaurants
{
  NSEntityDescription *entity = [NSEntityDescription entityForName:@"Restaurant" inManagedObjectContext:self.managedObjectContext];
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
  [fetchRequest setEntity:entity];

  NSError *error;
  foundObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];

  //[self.mapView addAnnotations:foundObjects];
}


- (void)queryGooglePlaces
{

  // Build the url string we are going to sent to Google. NOTE: The kGOOGLE_API_KEY is a constant which should contain your own API key that you can obtain from Google. See this link for more info:
  // https://developers.google.com/maps/documentation/places/#Authentication
  NSString *url = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/place/search/json?location=%f,%f&radius=%d&type=restaurant&sensor=true&key=%@", currentCenter.latitude, currentCenter.longitude, 1000 /*[NSString stringWithFormat:@"%i", currentDist]*/, kGOOGLE_API_KEY];

  //Formulate the string as URL object.
  //NSURL *googleRequestURL=[NSURL URLWithString:url];
  NSURL *googleRequestURL = [NSURL URLWithString:[url stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding]];

  // Retrieve the results of the URL.
  dispatch_async(kBgQueue, ^{
    NSData* data = [NSData dataWithContentsOfURL: googleRequestURL];
    [self performSelectorOnMainThread:@selector(fetchedData:) withObject:data waitUntilDone:YES];
  });
}

- (void)fetchedData:(NSData *)responseData
{
  NSError *error;
  NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];

  NSArray *places = [json objectForKey:@"results"];
  [self plotPositions:places];
}

- (void)plotPositions:(NSArray *)data {
  for (id<MKAnnotation> annotation in mapView.annotations)
  {
    if ([annotation isKindOfClass:[MapPoint class]])
    {
      [mapView removeAnnotation:annotation];
    }
  }


  //Loop through the array of places returned from the Google API.
  for (int i=0; i<[data count]; i++)
  {

    //Retrieve the NSDictionary object in each index of the array.
    NSDictionary* place = [data objectAtIndex:i];

    //There is a specific NSDictionary object that gives us location info.
    NSDictionary *geo = [place objectForKey:@"geometry"];


    //Get our name and address info for adding to a pin.
    NSString *name = [place objectForKey:@"name"];
    NSString *vicinity = [place objectForKey:@"vicinity"];

    //Get the lat and long for the location.
    NSDictionary *loc = [geo objectForKey:@"location"];

    //Create a special variable to hold this coordinate info.
    CLLocationCoordinate2D restaurantCoord;

    //Set the lat and long.
    restaurantCoord.latitude=[[loc objectForKey:@"lat"] doubleValue];
    restaurantCoord.longitude=[[loc objectForKey:@"lng"] doubleValue];

    //Create a new annotiation.
    MapPoint *placeObject = [[MapPoint alloc] initWithName:name address:vicinity coordinate:restaurantCoord];
    NSLog(@"mapPoint: %@", placeObject.name);
    if ([foundObjects count] > 0 ) {
      for (Restaurant *restaurant in foundObjects) {
       // NSLog(@"Restaurant: %@", restaurant);
        //NSLog(@"mapPoint: %@", placeObject.name);
        if (restaurant.restaurantName == placeObject.name) {
          return;
        } else {
          [mapView addAnnotation:placeObject];
        }
      }
    } else {
      [mapView addAnnotation:placeObject];
    }

  }
}

Restaurant是我的核心数据实体。我正在尝试将餐厅的名称与谷歌查询 api 返回的 mapPoint 的名称进行比较。我尝试 NSLogging 餐厅名称（核心数据）和谷歌 api 餐厅名称的返回值 - 它们似乎匹配。任何建议，或者我是否应该以不同的方式解决这个问题 - 让我知道谢谢！

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1 回答 1

1

问题是这一行：

if (restaurant.restaurantName == placeObject.name)

这只是比较两个指向字符串的指针。它总是返回 false。相反，您必须比较字符串是否相等：

if ([restaurant.restaurantName isEqualToString:placeObject.name])
于 2013-08-18T19:54:53.717 回答