Adding multiple annotations with multiple images on mapview in ios Objective-c?

Question

I am working on an old application and need to make changes in Mapview. Previously we need to show multiple annotations on mapview with same images on each pin but now we have to show different images on annotation view pins to display address. I am using the following code to display annotation pins but it always shows the same image on annotation pins.

Here is my code:

- (MKAnnotationView *) mapView:(MKMapView *)mapView1 viewForAnnotation:(id <MKAnnotation>) annotation
{
    NSLog(@"Eventtype Array is %@",eventTypeArray);
    MKAnnotationView * pinView = nil;
    if(annotation != _mapvw.userLocation)
    {
        static NSString * defaultPinID = @"pinId";
        pinView = (MKAnnotationView *)[_mapvw dequeueReusableAnnotationViewWithIdentifier:defaultPinID];

        if ( pinView == nil )
        {
            pinView = [[MKAnnotationView alloc]
                       initWithAnnotation:annotation reuseIdentifier:defaultPinID];
        }

    for ( int i=0; i<[eventTypeArray count]; i++)
        {
            eventTypeStr = [NSString stringWithFormat:@"%@",
                             [eventTypeArray objectAtIndex:i]];
            NSLog(@"Event Type is %@",eventTypeStr);

        if ([eventTypeStr isEqualToString:@"0"])
        {
            NSLog(@"Eventtype Array is %@",eventTypeStr);
            NSLog(@"Event Type is %@",eventTypeStr);
            pinView.canShowCallout = YES;
            pinView.image = [UIImage imageNamed:@"smiley.png"];
        }
        else if ([eventTypeStr isEqualToString:@"1"])
        {
            NSLog(@"Event Type is %@",eventTypeStr);
            pinView.canShowCallout = YES;
            pinView.image = [UIImage imageNamed:@"dollar1.png"];
        }
        else if ([eventTypeStr isEqualToString:@"2"])
        {
            NSLog(@"Event Type is %@",eventTypeStr);
            pinView.canShowCallout = YES;
            pinView.image = [UIImage imageNamed:@"donation.png"];
        }
        }
    }
    return pinView;
}

Just finish the for loop before if else. P.S. There are many other many other improvements possible in this code (like using switch case instead of if else, enum / constant for your event identifier wtc.). Please consider a thorough review, and refactoring. — Swapnil Luktuke

Rob Rob · Accepted Answer · 2020-05-01T16:35:42

You’re iterating through your array of event types for every annotation, presumably always ending with the image associated for the last one in eventTypeArray.

Instead, you want the “event type” to be a property of the annotation. Then, when generating your annotation view, you can look at the annotation’s event type to know which image to use.

So, first, you haven’t done so already, you’d have an annotation that has an eventType property:

typedef NS_ENUM(NSUInteger, EventType) {
    EventTypeSmiley,
    EventTypeDollar,
    EventTypeDonation,
};

@interface EventAnnotation: MKPointAnnotation
@property (nonatomic) EventType eventType;
@end

@implementation EventAnnotation
@end

Now, in this case, I’m using an enumeration for my event types, but you can use whatever type you want. (Even if you stick with the event type array, I’d still use an enumeration to excise cryptic 0/1/2 values sprinkled throughout your code.)

Then, when you add annotations to your map, use this new annotation type, not MKPointAnnotation:

EventAnnotation *eventAnnotation = [[EventAnnotation alloc] init];
eventAnnotation.coordinate = coordinate;
eventAnnotation.title = @"Fund raiser";
eventAnnotation.eventType = EventTypeDollar;

Now that all of your annotations are EventAnnotation, you can have your viewForAnnotation act accordingly:

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {
    if ([annotation isKindOfClass:[MKUserLocation class]]) {
        return nil;
    }

    NSAssert([annotation isKindOfClass:[EventAnnotation class]], @"Was expecting event annotation”);  // obviously, handle non-EventAnnotation annotations however you want, but I’m going to catch failures for now

    static NSString *identifier = @"EventAnnotation";
    MKAnnotationView *annotationView = [_mapView dequeueReusableAnnotationViewWithIdentifier:identifier];

    if (!annotationView) {
        annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier];
        annotationView.canShowCallout = YES;
    } else {
        annotationView.annotation = annotation;     // don't forget this line!
    }

    EventAnnotation *eventAnnotation = (EventAnnotation *)annotation;
    switch (eventAnnotation.eventType) {
        case EventTypeSmiley:
            annotationView.image = [UIImage imageNamed:@"smiley.png"];
            break;

        case EventTypeDollar:
            annotationView.image = [UIImage imageNamed:@"dollar1.png"];
            break;

        case EventTypeDonation:
            annotationView.image = [UIImage imageNamed:@"donation.png"];
            break;
    }

    return annotationView;
}

Adding multiple annotations with multiple images on mapview in ios Objective-c?

1 Answers