我建议简单地在以下位置创建地图视图viewDidLoad
:
- (void)viewDidLoad
{
[super viewDidLoad];
MKMapView * map = [[MKMapView alloc] initWithFrame:self.view.bounds];
map.delegate = self;
[self.view addSubview:map];
}
但是当用户移动地图时,寻找 Walmarts 并添加注释:
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
// if on slow network, it's useful to keep track of the previous
// search, and cancel it if it still exists
[self.previousSearch cancel];
// create new search request
MKLocalSearchRequest *request = [[MKLocalSearchRequest alloc] init];
request.naturalLanguageQuery = @"Walmart";
request.region = mapView.region;
// initiate new search
MKLocalSearch *localSearch = [[MKLocalSearch alloc] initWithRequest:request];
[localSearch startWithCompletionHandler:^(MKLocalSearchResponse *response, NSError *error) {
NSMutableArray *annotations = [NSMutableArray array];
[response.mapItems enumerateObjectsUsingBlock:^(MKMapItem *item, NSUInteger idx, BOOL *stop) {
// if we already have an annotation for this MKMapItem,
// just return because you don't have to add it again
for (id<MKAnnotation>annotation in mapView.annotations)
{
if (annotation.coordinate.latitude == item.placemark.coordinate.latitude &&
annotation.coordinate.longitude == item.placemark.coordinate.longitude)
{
return;
}
}
// otherwise, add it to our list of new annotations
// ideally, I'd suggest a custom annotation or MKPinAnnotation, but I want to keep this example simple
[annotations addObject:item.placemark];
}];
[mapView addAnnotations:annotations];
}];
// update our "previous" search, so we can cancel it if necessary
self.previousSearch = localSearch;
}
显然,此代码示例假定您有一个weak
用于先前搜索操作的属性。(严格来说,这不是必需的,但如果在 Internet 连接速度较慢时在地图上浏览,可能会给您带来更好的性能。)无论如何,该属性将定义如下:
@property (nonatomic, weak) MKLocalSearch *previousSearch;
还有其他可能的改进(例如UIActivityIndicatorView
,如果搜索正在进行,则为网络活动指示器,可能删除不在地图当前区域内的注释等),但希望您能理解。