Annotations in MapView - objective-c

Question

I have this code:
-(void)handleLongPressGesture:(UIGestureRecognizer*)sender {
NSNumber* existingpoints = [[NSNumber alloc]init];
existingpoints =[NSNumber numberWithInt:0];
// This is important if you only want to receive one tap and hold event
if (sender.state == UIGestureRecognizerStateEnded)
{
[self.mapView removeGestureRecognizer:sender];
}
else {
do {
int z = 1;
existingpoints =[NSNumber numberWithInt:z];
// Here we get the CGPoint for the touch and convert it to latitude and longitude coordinates to display on the map
CGPoint point = [sender locationInView:self.mapView];
CLLocationCoordinate2D locCoord = [self.mapView convertPoint:point toCoordinateFromView:self.mapView];
// Then all you have to do is create the annotation and add it to the map
MKPointAnnotation *annotationPoint = [[MKPointAnnotation alloc] init]; annotationPoint.coordinate = locCoord;
NSString *latitude = [[NSString alloc] initWithFormat:#"%f",locCoord.latitude];
NSString *longitude = [[NSString alloc] initWithFormat:#"%f", locCoord.longitude];
annotationPoint.title = #"Event";
annotationPoint.subtitle = [NSString stringWithFormat:#"%# & %#", latitude, longitude];
[mapView addAnnotation:annotationPoint];
[[NSUserDefaults standardUserDefaults]setObject:latitude forKey:#"FolderLatitude"];
[[NSUserDefaults standardUserDefaults]setObject:longitude forKey:#"FolderLongitude"];
} while ([existingpoints intValue] == 0);
}
}
...but the problem is that when I hold, and then drag more than one pin is added. I want to add only one pin. So I tried the do method but it doesn't work. I can't understand, because when I executed the code I turn the value of the NSNumber to 1, and the while says = 0 to run the code.
Please Help!!

Answer 1

Your current code is prone to have quite a number of memory leaks. For example:
NSNumber* existingpoints = [[NSNumber alloc] init];
existingpoints = [NSNumber numberWithInt:0];
Is leaking because you leave the first instance of existingpoints with retain value of 1 and not freeing it anywhere. Unless you're using ARC. You can optimize the above code with just one instruction:
NSNumber* existingpoints = [NSNumber numberWithInt:0];
And retain it if you need to keep it somewhere (but i belive it's not the case).
Analyzing the code, I'd recommend NOT to use existingpoints as an NSNumber. Use an NSInteger instead (which is not an object, just a typedef to long).
Here's my rewritten code:
-(void)handleLongPressGesture:(UIGestureRecognizer*)sender {
NSInteger existingpoints = 0;
// This is important if you only want to receive one tap and hold event
if (sender.state == UIGestureRecognizerStateEnded) {
[self.mapView removeGestureRecognizer:sender];
}
else {
do {
int z = 1;
existingpoints = z;
// Here we get the CGPoint for the touch and convert it to latitude and longitude coordinates to display on the map
CGPoint point = [sender locationInView:self.mapView];
CLLocationCoordinate2D locCoord = [self.mapView convertPoint:point toCoordinateFromView:self.mapView];
// Then all you have to do is create the annotation and add it to the map
MKPointAnnotation *annotationPoint = [[MKPointAnnotation alloc] init];
annotationPoint.coordinate = locCoord;
NSString *latitude = [NSString stringWithFormat:#"%f",locCoord.latitude];
NSString *longitude = [NSString stringWithFormat:#"%f", locCoord.longitude];
annotationPoint.title = #"Event";
annotationPoint.subtitle = [NSString stringWithFormat:#"%# & %#", latitude, longitude];
[mapView addAnnotation:annotationPoint];
[[NSUserDefaults standardUserDefaults] setObject:latitude forKey:#"FolderLatitude"];
[[NSUserDefaults standardUserDefaults] setObject:longitude forKey:#"FolderLongitude"];
[annotationPoint release]; // Remove this if you're using ARC.
} while (existingpoints == 0);
}
}
Note that I've also changed the code for creating latitude and longitude for not to create any memory leaks when using ARC.
EDIT:
Further analyzing your code, I don't see why this method would be dropping two pins at once. Maybe you could check if your method is not being called twice?
More: Why do you have a do/while loop if you just want it to run once? (but maybe you're just paving your ground to further ahead)