//清理坐標(biāo)數(shù)據(jù)的視圖和數(shù)據(jù)    [_bMapView removeAnnotations:_mapAnnotations];    [_mapAnnotations removeAllObjects];    [_carPointArray removeAllObjects];    //聲明解析時(shí)對(duì)坐標(biāo)數(shù)據(jù)的位置區(qū)域的篩選，包括經(jīng)度和緯度的最小值和最大值    CLLocationDegrees minLat;    CLLocationDegrees maxLat;    CLLocationDegrees minLon;    CLLocationDegrees maxLon;    //解析數(shù)據(jù)    for (int i=0; i<rows.count; i++) {        NSDictionary *row = [rows objectAtIndex:i];        坐標(biāo)模型類(lèi) *item = [[坐標(biāo)模型類(lèi) alloc] initWithJson:row];        if (item.vehicleNo && [item.vehicleNo length]>0) {            標(biāo)注模型類(lèi) *annotation = [[標(biāo)注模型類(lèi) alloc] init];            annotation.coordinate = item.baiduCoordinate;            annotation.item = item;            [_mapAnnotations addObject:annotation];            [_bMapView addAnnotation:annotation];            [annotation release];                        if (i==0) {                //以第一個(gè)坐標(biāo)點(diǎn)做初始值                minLat = item.baiduCoordinate.latitude;                maxLat = item.baiduCoordinate.latitude;                minLon = item.baiduCoordinate.longitude;                maxLon = item.baiduCoordinate.longitude;            }else{                //對(duì)比篩選出最小緯度，最大緯度；最小經(jīng)度，最大經(jīng)度                minLat = MIN(minLat, item.baiduCoordinate.latitude);                maxLat = MAX(maxLat, item.baiduCoordinate.latitude);                minLon = MIN(minLon, item.baiduCoordinate.longitude);                maxLon = MAX(maxLon, item.baiduCoordinate.longitude);            }                        [_carPointArray addObject:item];        }        [item release];    }    //動(dòng)態(tài)的根據(jù)坐標(biāo)數(shù)據(jù)的區(qū)域，來(lái)確定地圖的顯示中心點(diǎn)和縮放級(jí)別    if (_carPointArray.count > 0) {        //計(jì)算中心點(diǎn)        CLLocationCoordinate2D centCoor;        centCoor.latitude = (CLLocationDegrees)((maxLat+minLat) * 0.5f);        centCoor.longitude = (CLLocationDegrees)((maxLon+minLon) * 0.5f);        BMKCoordinateSpan span;        //計(jì)算地理位置的跨度        span.latitudeDelta = maxLat - minLat;        span.longitudeDelta = maxLon - minLon;        //得出數(shù)據(jù)的坐標(biāo)區(qū)域        BMKCoordinateRegion region = BMKCoordinateRegionMake(centCoor, span);        //百度地圖的坐標(biāo)范圍轉(zhuǎn)換成相對(duì)視圖的位置        CGRect fitRect = [_bMapView convertRegion:region toRectToView:_bMapView];        //將地圖視圖的位置轉(zhuǎn)換成地圖的位置        BMKMaPRect fitMapRect = [_bMapView convertRect:fitRect toMapRectFromView:_bMapView];        //設(shè)置地圖可視范圍為數(shù)據(jù)所在的地圖位置        [_bMapView setVisibleMapRect:fitMapRect animated:YES];            }

MKMapRect zoomRect = MKMapRectNull;for (id <MKAnnotation> annotation in mapView.annotations) {    MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);    MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0, 0);    if (MKMapRectIsNull(zoomRect)) {        zoomRect = pointRect;    } else {        zoomRect = MKMapRectUnion(zoomRect, pointRect);    }}[mapView setVisibleMapRect:zoomRect animated:YES];