fit to zoom in maps on iphone - iphone

Question

I am currently working on google maps.Using the GPS, I obtain the user's lat long information and hit a web service to obtain the nearest 5 stores available. I am able to plot the pins for it but the problem is how to fit the 5 pins to a maximum zoom scale ? I mean how does one obtain the latitude and longitude delta of the span in order to zoom as well as fit all the pins at the same time?

Answer 1

Try the following...
-(void)zoomToFitMapAnnotations:(MKMapView*)mapView
{
if([mapView.annotations count] == 0)
return;
CLLocationCoordinate2D topLeftCoord;
topLeftCoord.latitude = -90;
topLeftCoord.longitude = 180;
CLLocationCoordinate2D bottomRightCoord;
bottomRightCoord.latitude = 90;
bottomRightCoord.longitude = -180;
for(DisplayMap* annotation in mapView.annotations)
{
topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude);
bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude);
bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude);
}
MKCoordinateRegion region;
region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5;
region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;
region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1;
region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1;
region = [mapView regionThatFits:region];
[mapView setRegion:region animated:YES];
}

Answer 2

There is a good post on how to do this here
The finished code I used to achieve this is here...
-(void)zoomToFitMapAnnotations:(MKMapView*)mv
{
if([mv.annotations count] == 0)
return;
CLLocationCoordinate2D topLeftCoord;
topLeftCoord.latitude = -90;
topLeftCoord.longitude = 180;
CLLocationCoordinate2D bottomRightCoord;
bottomRightCoord.latitude = 90;
bottomRightCoord.longitude = -180;
for(MapViewAnnotate* annotation in mv.annotations)
{
topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude);
bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude);
bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude);
}
MKCoordinateRegion region;
region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5;
region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;
region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1; // Add a little extra space on the sides
region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1; // Add a little extra space on the sides
region = [mv regionThatFits:region];
[mv setRegion:region animated:YES];
}
This assumes you're using annotation objects in from an annotation class similar to this (stored in an array)....
MapViewAnnotate.h
#interface MapViewAnnotate : NSObject <MKAnnotation>
{
NSString *title;
NSString *subtitle;
CLLocationCoordinate2D coordinate;
}
#property (nonatomic, copy) NSString *title;
#property (nonatomic, copy) NSString *subtitle;
#property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
- (id)initWithCoordinate:(CLLocationCoordinate2D)c title:(NSString *)t subtitle:(NSString *)s;
#end
MapViewAnnotate.m
#import "PropertyMapViewAnnotate.h"
#implementation MapViewAnnotate
#synthesize coordinate, title, subtitle;
- (id)initWithCoordinate:(CLLocationCoordinate2D)c title:(NSString *)t subtitle:(NSString *)s
{
[super init];
coordinate = c;
[self setTitle:t];
[self setSubtitle:s];
return self;
}
- (void)dealloc
{
[title release];
[subtitle release];
[super dealloc];
}
#end