如何使用 MKPointAnnotation 向 MKMapView 添加注释？

Question

我试图弄清楚如何将 MKAnnotation 的实例添加到 MKMapView。我无法弄清楚我做错了什么......在我真正尝试将注释添加到mapView之前，一切似乎都很好。然后我收到一个 SIGABRT 错误。这是我的代码：

lon = [[attributeDict objectForKey:@"long"] doubleValue];
lat = [[attributeDict objectForKey:@"lat"] doubleValue];
 MKPointAnnotation *point;
 CLLocation *theLocation = [[CLLocation alloc]initWithLatitude:lat longitude:lon];
 CLLocationCoordinate2D location;
 location.latitude = lat;
 location.longitude = lon;
 [point setCoordinate:(location)];
 [point setTitle:businessName];

 //ITS RIGHT HERE THAT I GET THE ERROR
 [theMap addAnnotation:point];

你必须先设置地图的区域还是什么？

Answer 1

你需要分配和初始化point:

MKPointAnnotation *point = [[MKPointAnnotation alloc] init];