iOS Location Services and map development (3)---Geographic information encoding query

That is, the relevant geographic coordinates are obtained based on a nsstring literal description object.

Using the Clgeocoder class operation, the specific method:

1>geocodeaddressdictionary:completionhandler: Querying by specifying an address information Dictionary object parameter

2>geocodeaddressstring:completionhandler: Querying by specifying an address information string parameter

3>geocodeaddressstring:inregion:completionhandler: Querying by making address information strings and query scopes

-(Ibaction) Geocodequery: (ID) sender{NSString*querystr =Nil; //Enter an address string from the interface text box    if(_textfield.text = = Nil | | [_textfield.text length] = =0) {        return ; } Clgeocoder*geocoder =[[Clgeocoder alloc] init]; [Geocoder geocodeaddressstring:querystr Completionhandler:^ (Nsarray *placemarks, Nserror *error) {NSLog (@"Query record number:%i", [placemarks Count]); if([Placemarks Count] >0) {Clplacemark*placemark = [Placemarks objectatindex:0]; cllocationcoordinate2d coordinate=placemark.location.coordinate; //generate latitude and longitude stringsNSString *strcoordinate = [NSString stringWithFormat:@"Longitude:%3.5f, Latitude:%3.5f", Coordinate.latitude,coordinate.longitude]; Nsdictionary*addressdict =placemark.addressdictionary; NSString*address = [addressdict objectforkey: (NSString *) Kabpersonaddressstreetkey]; Address= Address = = Nil?@"": Address; NSString*state = [addressdict objectforkey: (NSString *) Kabpersonaddressstatekey]; State= state = = Nil?@"": State; NSString*city = [addressdict objectforkey: (NSString *) Kabpersonaddresscitykey]; City= City = = Nil?@"": City; //gets a landmark corresponding to a readable text message that is typically returned to the UI displayNSString *streetinfo = [NSString stringWithFormat:@"%@\n%@\n%@\n%@\n", strcoordinate,state,address,city]; }    }];}

Use GeocodeAddressString:inRegion:completionHandler: Specify the query area:

Clregion *region = [[Clregion alloc] initcircularregionwithcenter:_currlocation.coordinate radius:1000.0f Identifier:@ "geocoderegion"];     *geocoder = [[Clgeocoder alloc] init];    [Geocoder geocodeaddressstring:querystr inregion:region Completionhandler:^ (Nsarray *placemarks, NSError *  Error) {        ...    }];

The Clregion object encapsulates a geographic region class.

Constructor method Parameters:

Center: Specify a regional center point

Radius: Specify the radius of the area in meters

Identifier: Specify an identity for the zone