fit to zoom in maps on iphone

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开发者_如何学JAVA obtain the latitude and longitude delta of the span in order to zoom as well as fit all the pins at the same time?

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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];
    }

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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