Question

我有一个500个注释的NSArray，我基本上只想向用户显示十个最近的注释（其余的不会添加到Mapview上）

我该怎么做？

这是我的代码：

-(void) loadAndSortPOIs {
 [poiArray release];
 nextPoiIndex = 0;
 NSString *poiPath = [[NSBundle mainBundle] pathForResource:@"annotations"
              ofType:@"plist"];
 poiArray = [[NSMutableArray alloc] initWithContentsOfFile:poiPath];
 CLLocation *homeLocation = [[CLLocation alloc] 
        initWithLatitude:homeCoordinate.latitude
        longitude:homeCoordinate.longitude];
 for (int i = 0; i < [poiArray count]; i++) {
  NSDictionary *dict = (NSDictionary*) [poiArray objectAtIndex: i];
  CLLocationDegrees storeLatitude = [[dict objectForKey:@"workingCoordinate.latitude"] doubleValue];
  CLLocationDegrees storeLongitude = [[dict objectForKey:@"workingCoordinate.longitude"] doubleValue];
  CLLocation *storeLocation = [[CLLocation alloc]
          initWithLatitude:storeLatitude
          longitude:storeLongitude];
  CLLocationDistance distanceFromHome = [storeLocation distanceFromLocation: homeLocation];
  [storeLocation release];


  NSMutableDictionary *mutableDict = [[NSMutableDictionary alloc]
           initWithDictionary:dict];
  [mutableDict setValue:[NSNumber numberWithDouble:distanceFromHome]
        forKey:@"distanceFromHome"];
  [poiArray replaceObjectAtIndex:i withObject:mutableDict];
  [mutableDict release];

 }


// now sort by distanceFromHome

 NSArray *sortDescriptors = [NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:@"distanceFromHome" ascending:YES] autorelease]];

 [poiArray sortUsingDescriptors:sortDescriptors];
 NSLog (@"poiArray: %@", poiArray);

 [homeLocation release];

编辑：我已将此添加到我的代码中，但它仍然无效......

- (void) displayPois {
    [mapView removeAnnotations: mapView.annotations];
for(int i = 0; i < 10; i++) {
    NSDictionary *poiDict = [poiArray objectAtIndex:nextPoiIndex++];
    CLLocationCoordinate2D poiCoordinate;
    poiCoordinate.latitude = [[poiDict valueForKey:@"workingCoordinate.latitude"] doubleValue];
    poiCoordinate.longitude = [[poiDict valueForKey:@"workingCoordinate.longitude"] doubleValue];
    MyHomeAnnotation *poiAnnotation = [[MyHomeAnnotation alloc]
                                       initWithCoordinate:poiCoordinate
                                       title:[poiDict valueForKey:@"Subtitle"]
                                       ];
        [mapView addAnnotation:poiAnnotation];
        [self loadAndSortPOIs];
    [poiAnnotation release];

    }   [self adjustMapZoom];
}

Answer 1

addAnnotations方法需要符合MKAnnotation协议的对象数组。您传递的数组似乎只包含普通的字典对象。

您需要使用遍历注释数组的循环替换addAnnotations行，并从每个字典对象创建一个MKPointAnnotation对象（拉出坐标并使用它们初始化MKPointAnnotation对象）。然后（在for循环中）调用addAnnotation（单数）并将其传递给MKPointAnnotation对象。

在Mapview中显示有限数量的已排序注释

1 个答案: