Zooming MkMapView from another class - xcode

Question

I have a ViewController with UITableView *myTable and MKMapView *myMap designed in xib, but the table delegate/datasource and the map delegate are in another class, named SubClass. When I press a button in ViewController the SubClass parse in the tablecells latitude and longitude from a xml remote file, and now I want to zoom myMap into this coordinates every time I select the rows of myTable: Well, I can't find a way to call this zoom FROM SubClass. This is, simplified, my code:
ViewController.h
// ViewController.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#import "SubClass.h"
#interface ViewController : UIViewController {
IBOutlet UITableView *myTable;
IBOutlet MKMapView *myMap;
SubClass *subClassIstance;
}
- (void)buttonPressed:(id)sender
#property (nonatomic, retain) IBOutlet MKMapView *myMap;
ViewController.m
// in ViewController.m
- (void)buttonPressed:(id)sender {
subClassIstance = [[SubClass alloc] init];
myTable.delegate = SubClass;
myTable.dataSource = SubClass;
[myTable reloadData];
subClassIstance = [[SubClass alloc] loadMap:myMap];
}
SubClass.h
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#interface SubClass : NSObject <UITableViewDataSource, UITableViewDelegate, MKMapViewDelegate> {
}
- (void)loadValues;
- (id)loadMap:(MKMapView *)mapView;
- (id)zoomTheMap:(NSMutableString *)string1 :(NSMutableString *)string2 :(MKMapView *)mapView; // IS IT RIGHT???
SubClass.m
- (id)init{
self = [super init];
if ( self != nil ) {
[self loadValues];
}
return self;
}
- (void)loadValues {
// CODE TO PARSE VALUES OF LONGITUDE AND LATITUDE TO PASS IN THE TABLE CELLS
latitudeFromLoadValues = // NSMutableString parsed value from a xml remote file
longitudeFromLoadValues = // NSMutableStringparsed value from a xml remote file
}
- (id)loadMap:(MKMapView *)mapView
{
if (self) {
mapView.delegate = self; // CODE TO LOAD ANNOTATIONS AND OTHER STUFF. IT WORKS!
}
return self;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
latitudeFromLoadValues = [dataParsed objectAtIndex:indexPath.row];
longitudeFromLoadValues = [data2Parsed objectAtIndex:indexPath.row];
[self zoomTheMap:latitudeFromLoadValues :longitudefromLoadValues :???]; // IS IT CORRECT? WHAT IS THE RIGHT *MKMAPVIEW?
}
- (id)zoomTheMap:(NSMutableString *)string1 :(NSMutableString *)string2 :(MKMapView *)mapView {
NSLog(#"%#",string1);
NSLog(#"%#",string2);
MKCoordinateRegion region;
region.center.latitude = [string1 floatValue];
region.center.longitude = [string2 floatValue];
region.span.latitudeDelta = 2.0;
region.span.longitudeDelta = 2.0;
// I KNOW, I HAVE TO CALL myMap from ViewController! But with an istance?
mapView.delegate = self;
mapView.region = region;
return self;
}
Well, the rest of code works! I can see *myMap in ViewController loaded with some annotations declared in SubClass and *myTable loaded with cells populated with latitude and longitude parsed in SubClass; I can also see correct longitude and latitude passed in string1 and string2 but when I select the single table cell I don't see myMap zooming, I think I am using the wrong method. Can U help me, please?

Answer 1

loadMap shouldn't return self, only init methods should do that.
In buttonPressed you allocate a new SubClass, do some stuff to it, then allocate another SubClass and call its loadMap function. The last line should be [subClassIstance loadMap:myMap], but you'll also want to reconsider allocating a new SubClass every time that button is pressed.
I think you're really going about this the wrong way. Why do you need a SubClass (terrible name BTW, it says nothing about what it is for)? What class does it extend? If the ViewController has the MKMapView, it is usually the one to issue commands to the map. I can understand you having a separate datasoucre for the tableview, but not the rest. If you make the VC its own table and map delegate you'll simplify things a lot.
If you really want to have a subclass in your code then you should be calling loadMap on the instance you created on the first line of buttonPressed
- (void)buttonPressed:(id)sender {
subClassIstance = [[SubClass alloc] init];
myTable.delegate = SubClass;
myTable.dataSource = SubClass;
[myTable reloadData];
[subClassIstance loadMap:myMap];
}
and your loadMap would look like
- (void)loadMap:(MKMapView *)mapView
{
mapView.delegate = self;
}
However if that's all loadMap does you don't need a function for that, you could just make buttonPressed do it all.
- (void)buttonPressed:(id)sender {
subClassIstance = [[SubClass alloc] init];
myTable.delegate = SubClass;
myTable.dataSource = SubClass;
[myTable reloadData];
myMap.delegate = subClassIstance;
}
Example init function:
- (id)initiWithMapView: (MKMapView)* mapView
{
self = [super init];
if(self)
{
theMap = mapView;
theMap.delegate = self;
[self loadValues];
....
}
return self;
}
If you use this you won't have to set the map delegate or return self all the time and you can use theMap (as declared in your answer) in every function.

Answer 2

Well, I have found a simply solution, for those interested: first, I have defined a generic MKMapView *theMap in my SubClass.h, that now looks like:
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#interface SubClass : NSObject <UITableViewDataSource, UITableViewDelegate,
MKMapViewDelegate> {
MKMapView *theMap // NEW CODE!!!
}
- (void)loadValues;
- (id)loadMap:(MKMapView *)mapView;
- (id)zoomTheMap:(NSMutableString *)string1 :(NSMutableString *)string2 :(MKMapView *)mapView;
In loadMap method I have compared *theMap to mapView called by the SubClassIstance in VC (my *myMap that I want to zoom), so now we have:
- (id)loadMap:(MKMapView *)mapView
{
if (self) {
mapView.delegate = self;
theMap = mapView; // NEW CODE !!!
// CODE TO LOAD ANNOTATIONS AND OTHER STUFF. IT WORKS!
}
return self;
}
In didSelectRowAtIndexPath I have passed *theMap as mapView argument of zoomTheMap method:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
latitudeFromLoadValues = [dataParsed objectAtIndex:indexPath.row];
longitudeFromLoadValues = [data2Parsed objectAtIndex:indexPath.row];
[self zoomTheMap:latitudeFromLoadValues :longitudefromLoadValues :theMap]; // NEW CODE !!!
}
The zoomTheMap method doesn't change, and now, "magically", every time I press a row of my table, the *myMap designed in the VC xib (but with delegate in SubClass) zooms into the coordinates stored in the cells:
- (id)zoomTheMap:(NSMutableString *)string1 :(NSMutableString *)string2 :(MKMapView *)mapView {
MKCoordinateRegion region;
region.center.latitude = [string1 floatValue];
region.center.longitude = [string2 floatValue];
region.span.latitudeDelta = 2.0;
region.span.longitudeDelta = 2.0;
mapView.delegate = self; // here mapView is *theMap passed in didSelectRowAtIndexPath, AKA original mapView istance used to delegate *myMap in VC
[mapView setRegion:region animated:YES];
return self;
}
Maybe its not an "elegant" way, but it now works! ;=)