iPhone MKMapView：设置地图区域显示地图上的所有引脚

我正在设置地图区域（中心和跨度），以便地图同时显示所有引脚标注。

我有麻烦转换长/纬度坐标从NSString双，分别。 与他们计算。 这是我正在使用的代码：

- (void)updateMemberPins{ //calculate new region to show on map double center_long = 0.0f; double center_lat = 0.0f; double max_long = 0.0f; double min_long = 0.0f; double max_lat = 0.0f; double min_lat = 0.0f; for (Member *member in members) { //find min and max values if ([member.locLat doubleValue] > max_lat) {max_lat = [member.locLat doubleValue];} if ([member.locLat doubleValue] < min_lat) {min_lat = [member.locLat doubleValue];} if ([member.locLong doubleValue] > max_long) {max_long = [member.locLong doubleValue];} if ([member.locLong doubleValue] < min_long) {min_long = [member.locLong doubleValue];} //sum up long and lang to get average later center_lat = center_lat + [member.locLat doubleValue]; center_long = center_long + [member.locLong doubleValue]; } //calculate average long / lat center_lat = center_lat / [members count]; center_long = center_long / [members count]; NSLog(@"center long: %d, center lat: %d", center_long, center_lat); NSLog(@"max_long: %d, min_long: %d, max_lat: %d, min_lat: %d", max_long, min_long, max_lat, min_lat); //create new region and set map CLLocationCoordinate2D coord = {latitude: center_lat, longitude: center_long}; MKCoordinateSpan span = MKCoordinateSpanMake(abs(max_lat) + abs(min_lat), abs(max_long) + abs(min_long)); MKCoordinateRegion region = {coord, span}; [resultMapView setRegion:region]; //remove all pins from map [resultMapView removeAnnotations:resultMapView.annotations]; //show member pins for (id member in members) { [resultMapView addAnnotation:(Member *) member]; } 

}

日志输出的结果是：

中心长：-1946827116，中心纬度：1075651472

max_long：-6267216，min_long：1076018553，max_lat：0，min_lat：0

我认为问题来自（错误地）将NSString的值转换为double，但是我找不到使其工作的方法…位置string的格式类似于'43.5686473'。

任何提示？ Cheerz

Answer 1

要在NSLog（）中显示double值，你应该使用%f ，而不是%d改变NSLog()部分是这样的：

 NSLog(@"center long: %f, center lat: %f", center_long, center_lat); NSLog(@"max_long: %f, min_long: %f, max_lat: %f, min_lat: %f", max_long, min_long, max_lat, min_lat); 

而且，使用MKMapView区域比创build自己的区域要简单得多。 一旦设置了缩放比例，您只需要用不同的坐标在地图上dynamic移动即可。

 MKCoordinateRegion region = self.mapView.region; region.center = centerCoordinate; region.span.longitudeDelta /= ratioZoomMax; // Bigger the value, closer the map view region.span.latitudeDelta /= ratioZoomMax; [self.mapView setRegion:region animated:YES]; // Choose if you want animate or not 

Answer 2

那些寻找类似的东西的最后的工作代码：

  - (void)updateMemberPins{ //remove all pins from map [resultMapView removeAnnotations:resultMapView.annotations]; if ([members count] > 0) { @try { //calculate new region to show on map Member *firstMember = [members objectAtIndex:0]; double max_long = [firstMember.locLong doubleValue]; double min_long = [firstMember.locLong doubleValue]; double max_lat = [firstMember.locLat doubleValue]; double min_lat = [firstMember.locLat doubleValue]; //find min and max values for (Member *member in members) { if ([member.locLat doubleValue] > max_lat) {max_lat = [member.locLat doubleValue];} if ([member.locLat doubleValue] < min_lat) {min_lat = [member.locLat doubleValue];} if ([member.locLong doubleValue] > max_long) {max_long = [member.locLong doubleValue];} if ([member.locLong doubleValue] < min_long) {min_long = [member.locLong doubleValue];} } //calculate center of map double center_long = (max_long + min_long) / 2; double center_lat = (max_lat + min_lat) / 2; //calculate deltas double deltaLat = abs(max_lat - min_lat); double deltaLong = abs(max_long - min_long); //set minimal delta if (deltaLat < 5) {deltaLat = 5;} if (deltaLong < 5) {deltaLong = 5;} //debug //NSLog(@"center long: %f, center lat: %f", center_long, center_lat); //NSLog(@"max_long: %f, min_long: %f, max_lat: %f, min_lat: %f", max_long, min_long, max_lat, min_lat); //create new region and set map CLLocationCoordinate2D coord = {latitude: center_lat, longitude: center_long}; MKCoordinateSpan span = MKCoordinateSpanMake(deltaLat, deltaLong); MKCoordinateRegion region = {coord, span}; [resultMapView setRegion:region]; } @catch (NSException * e) { NSLog(@"Error calculating new map region: %@", e); } @finally { //show member pins for (id member in members) { [resultMapView addAnnotation:(Member *) member]; } } } } 

Answer 3

 //show member pins for (id member in members) { [resultMapView addAnnotation:(Member *) member]; } 

这可以被replace

 [resultMapView addAnnotations:members]; 

Answer 4

你可以简单地使用这个和平的代码：

 -(void)updateMemberPins { if([members count] == 0) return; double minLat = 90; double minLon = 180; double maxLat = -90; double maxLon = -180; for(Member *member in members) { minLat = fmin(minLat, [member.locLat doubleValue]); minLon = fmin(minLon, [member.locLong doubleValue]); maxLat = fmax(maxLat, [member.locLat doubleValue]); maxLon = fmax(maxLon, [member.locLong doubleValue]); } NSLog(@"MAX LAT: %f, MIN LAT: %f, MAX LONG: %f, MIN LONG: %f,", maxLat, minLat, maxLon, minLon); double midLat = (minLat + maxLat)/2; double midLong = (minLon + maxLon)/2; double deltaLat = abs(maxLat - minLat); double deltaLong = abs(maxLon - minLon); if (deltaLat < 5) {deltaLat = 5;} if (deltaLong < 5) {deltaLong = 5;} //... }