Set the correct zoom in a UIMapView

Set the correct zoom in a UIMapView

I made a count-steps app, I count the steps with the iPhone accelerometer
and now I want to display the path I made on a mapView. I can easily show
the map and catch the right position with the iPhone GPS, I can display
the start and the end point and I can to draw a polyline to show the path
I made. Now my problem is how to set a correct zoom on the map? When I
open the ViewController with map the zoom it's too far and I've to zoom to
see the path I made. So my question is how to set a correct zoom? I post
here the code of the View Controller with the mapView:
ResultViewController.m
#import "ResultViewController.h"
#import "MapAnnotation.h"
@interface ResultViewController ()
@property (nonatomic, strong)NSMutableArray *mapAnnotation;
@property (nonatomic) BOOL needUpdateRegion;
@end
@implementation ResultViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle
*)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.labelResult.text = self.totalSteps;
[self.mapView setDelegate:self];
self.needUpdateRegion = YES;
self.mapAnnotation = [[NSMutableArray alloc]initWithCapacity:2];
CLLocation *startLocation = [self.locationArray objectAtIndex:0];
CLLocation *stopLocation = [self.locationArray lastObject];
NSString *startLatitude = [NSString stringWithFormat:@"%f",
startLocation.coordinate.latitude];
NSString *startLongitude = [NSString stringWithFormat:@"%f",
startLocation.coordinate.longitude];
NSString *stopLatitude = [NSString stringWithFormat:@"%f",
stopLocation.coordinate.latitude];
NSString *stopLongitude = [NSString stringWithFormat:@"%f",
stopLocation.coordinate.longitude];
MapAnnotation *startPlace = [[MapAnnotation
alloc]initWithCoordinate:startLatitude andLong:startLongitude];
MapAnnotation *stopPlace = [[MapAnnotation
alloc]initWithCoordinate:stopLatitude andLong:stopLongitude];
[self.mapAnnotation insertObject:startPlace atIndex:0];
[self.mapAnnotation insertObject:stopPlace atIndex:1];
if (self.mapAnnotation) {
[self.mapView removeAnnotations:self.mapView.annotations];
}
[self.mapView addAnnotation:self.mapAnnotation[0]];
[self.mapView addAnnotation:self.mapAnnotation[1]];
[self updateRegion];
[self createMKpolylineAnnotation];
}
- (void)updateRegion
{
self.needUpdateRegion = NO;
CGRect boundingRect;
BOOL started = NO;
for (id <MKAnnotation> annotation in self.mapView.annotations) {
CGRect annotationRect = CGRectMake(annotation.coordinate.latitude,
annotation.coordinate.longitude, 0, 0);
if (!started) {
started = YES;
boundingRect = annotationRect;
} else {
boundingRect = CGRectUnion(boundingRect, annotationRect);
}
}
if (started) {
boundingRect = CGRectInset(boundingRect, -0.2, -0.2);
if ((boundingRect.size.width < 20) && (boundingRect.size.height <
20)) {
MKCoordinateRegion region;
region.center.latitude = boundingRect.origin.x +
boundingRect.size.width / 2;
region.center.longitude = boundingRect.origin.y +
boundingRect.size.height / 2;
region.span.latitudeDelta = boundingRect.size.width;
region.span.longitudeDelta = boundingRect.size.height;
[self.mapView setRegion:region animated:YES];
}
}
}
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id
<MKOverlay>)overlay {
MKPolylineView *polylineView = [[MKPolylineView alloc]
initWithPolyline:overlay];
polylineView.strokeColor = [UIColor blueColor];
polylineView.lineWidth = 5.0;
return polylineView;
}
- (void)createMKpolylineAnnotation {
NSInteger numberOfSteps = self.locationArray.count;
CLLocationCoordinate2D *coords = malloc(sizeof(CLLocationCoordinate2D)
* numberOfSteps);
for (NSInteger index = 0; index < numberOfSteps; index++) {
CLLocation *location = [self.locationArray objectAtIndex:index];
CLLocationCoordinate2D coordinate = location.coordinate;
coords[index] = coordinate;
}
MKPolyline *polyLine = [MKPolyline polylineWithCoordinates:coords
count:numberOfSteps];
[self.mapView addOverlay:polyLine];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)restart:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
}
@end
What's wrong with this code? There's someone that can help me to zoom the
map correctly?
Thank you