百度地图之标注一组地理坐标<2>

一、需求

开发移动地图相关的应用有时会有这种需求：在地图上显示自己的定位，然后想查看周边使用这个应用的有哪些人。当然完毕这个功能须要后台数据的支持。你要把自己的位置信息发给后台，后台在依据你的位置查询数据库返回你周围的用户的信息，这些信息包含经纬度坐标、描写叙述等。这里仅仅描写叙述client怎样实现。至于后台返回的这些数据就在本地创建家数据了，以下就用百度地图实现这个功能。

二、实现效果展示

三、代码（定位功能上一篇文章已经描写叙述。以下仅仅实现显示一组坐标）

1、创建变量接受协议

@interface BaiduMapViewController ()<BMKMapViewDelegate,BMKLocationServiceDelegate>
{
BMKMapView * _mapView; //地图
BMKLocationService * _locationService; //定位 NSMutableArray * _points;//地理坐标的集合
NSMutableArray * _titles;//标注
}
@property (nonatomic,strong) CLLocationManager *locationManager; //iOS8以后定位授权机制的改变，须要手动授权
@end

2、创建视图＋初始化对应数据

- (void)viewDidLoad {
[super viewDidLoad];
_mapView = [[BMKMapView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
[self.view addSubview:_mapView];
[_mapView setZoomLevel:14];
//定位
_locationService = [[BMKLocationService alloc]init]; //显示周围
UIButton * showAround = [UIButton buttonWithType:UIButtonTypeCustom];
[showAround setTitle:@"显示周围" forState:UIControlStateNormal];
[showAround setTitleColor:[UIColor greenColor] forState:UIControlStateNormal];
showAround.frame = CGRectMake(200, 0, 80, 30);
[showAround addTarget:self action:@selector(showAround) forControlEvents:UIControlEventTouchUpInside];
[self.navigationController.navigationBar addSubview:showAround]; //创建地理坐标和标注title
CGPoint item1 = CGPointMake(39.915101, 116.403981);
CGPoint item2 = CGPointMake(39.945210, 116.403981);
CGPoint item3 = CGPointMake(39.935301, 116.403991);
CGPoint item4 = CGPointMake(39.925421, 116.403971);
_points = [[NSMutableArray alloc] initWithObjects:NSStringFromCGPoint(item1), NSStringFromCGPoint(item2),NSStringFromCGPoint(item3),NSStringFromCGPoint(item4),nil]; _titles = [[NSMutableArray alloc]initWithObjects:@"天安门",@"神刹海",@"景山公园",@"故宫", nil];}

3、管理地图的生命周期：自2.0.0起。BMKMapView新增viewWillAppear、viewWillDisappear方法来控制BMKMapView的生命周期。而且在一个时刻仅仅能有一个BMKMapView接受回调消息。因此在使用BMKMapView的viewController中须要在viewWillAppear、viewWillDisappear方法中调用BMKMapView的相应的方法，并处理delegate

#pragma mark - viewWillAppear
-(void)viewWillAppear:(BOOL)animated{
[_mapView viewWillAppear];
_mapView.delegate = self;
_locationService.delegate = self;
}#pragma mark - viewDidAppear
-(void)viewWillDisappear:(BOOL)animated{
[_mapView viewWillDisappear];
_mapView.delegate = nil;
_locationService.delegate = nil;}

4、当点击“显示周边”button的时创建大头针

-(void)showAround{
if (_points.count) {
NSMutableArray * annotations = [[NSMutableArray alloc]init];
for (int i = 0; i < _points.count; i++) {
CGPoint point = CGPointFromString(_points[i]);
CLLocationCoordinate2D pt = (CLLocationCoordinate2D){point.x,point.y};
//创建大头针
BMKPointAnnotation * item = [[BMKPointAnnotation alloc]init];
//设置大头针的坐标
item.coordinate = pt;
//设置大头针的标注
item.title = _titles[i];
[annotations addObject:item];
if(i == 0)
{
//将第一个点的坐标移到屏幕中央
_mapView.centerCoordinate = pt;
} }
//加入大头针到地图上
[_mapView addAnnotations:annotations]; }
}#pragma mark 当调用[_mapView addAnnotations:annotations]时回出发地图的代理方法，创建大头针
-(BMKAnnotationView *)mapView:(BMKMapView *)mapView viewForAnnotation:(id<BMKAnnotation>)annotation{
NSString * ID = @"annotationViewID";
BMKPinAnnotationView * view = (BMKPinAnnotationView*)[mapView dequeueReusableAnnotationViewWithIdentifier:ID];
if (view == nil) {
view = [[BMKPinAnnotationView alloc]initWithAnnotation:annotation reuseIdentifier:ID];
view.pinColor = BMKPinAnnotationColorPurple;
view.animatesDrop = YES;
}
view.centerOffset = CGPointMake(0, -(view.frame.size.height*.5));
view.annotation = annotation; //设置代理
view.canShowCallout = TRUE;
return view;
}

关于地图的其它功能待续……