Question

此函数接受纬度/经度对数组。它将所有这些转换为MKAnnotation s，然后对于当前在地图上显示的每个注释，它会检查它是否存在于新的注释集中。如果它存在，则按原样保留注释，否则将其删除。

然后，对于每个新注释，它检查它当前是否在地图上;如果是，则保留它，否则将其删除。

这显然是非常密集的，我想知道是否有更快的方法吗？

- (void)setAnnotationWithArray:(NSArray *)array {
    static BOOL processing = NO;
    if (processing) {
        return;
    }
    dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        processing = YES;


        NSMutableArray *annotationsArray = [NSMutableArray arrayWithCapacity:[array count]];
        NSMutableArray *annotationsToRemove = [NSMutableArray array];

        for (NSDictionary *dict in array) {
            NSString *latStr = [dict objectForKey:@"Latitude"];
            NSString *lonStr = [dict objectForKey:@"Longitude"];
            NSString *title = [dict objectForKey:@"Location"];

            double lat = [latStr doubleValue];
            double lon = [lonStr doubleValue];


            CLLocationCoordinate2D location;
            location.latitude = lat;
            location.longitude = lon;

            MapViewAnnotation *newAnnotation = [[MapViewAnnotation alloc] initWithTitle:title andCoordinate:location];
            [annotationsArray addObject:newAnnotation];
            [newAnnotation release];
        }

        for (id<MKAnnotation> oldAnnotation in [mv annotations]) {
            CLLocationCoordinate2D oldCoordinate = [oldAnnotation coordinate];

            BOOL exists = NO;
            for (MapViewAnnotation *newAnnontation in annotationsArray) {
                CLLocationCoordinate2D newCoordinate = [newAnnontation coordinate];
                if ((newCoordinate.latitude == oldCoordinate.latitude)
                    && (newCoordinate.longitude == oldCoordinate.longitude)) {
                    exists = YES;
                    break;
                }
            }

            if (!exists) {
                [annotationsToRemove addObject:oldAnnotation];
            }
        }


        [annotationsArray removeObjectsInArray:[mv annotations]];
        dispatch_async( dispatch_get_main_queue(), ^{
            processing = NO;
            [mv removeAnnotations:annotationsToRemove];
            [mv addAnnotations:annotationsArray];
        });
    });



}

Answer 1

你可以使用removeObjectsInArray：（NSArray *）。

例如：

NSMutableArray *annotationsToRemove = [[NSMutableArray alloc] initWithArray:[mapView annotations]];
[annotationsToRemove removeObjectsInArray:annotationsArray];
NSMutableArray *annotationsToAdd = [[NSMutableArray alloc] initWithArray:annotationsArray];
[annotationsToAdd removeObjectsInArray:[mapView annotations]];

它假设您的注释实现了hash和isEqual：但应该更有效。

MKAnnotation删除（处理器重）

1 个答案: