Trying to change MKPointAnnotation colour but losing the title

问题

I am trying to change my pin colour to purple, when I do it I lose the title though. Code is:

- (void)viewDidLoad {
    [super viewDidLoad];

    self.navigationController.navigationBarHidden=YES;

    //init the location manager
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    [self.locationManager requestWhenInUseAuthorization];
    self.mapView.showsUserLocation=YES;

    self.userGeoPoint=self.message[@"userLocation"];
    self.pinView = [[MKPointAnnotation alloc] init];

    self.pinView.title=self.message[@"fromUser"];
    self.coord = CLLocationCoordinate2DMake(self.userGeoPoint.latitude, self.userGeoPoint.longitude);
    self.pinView.coordinate=self.coord;
    //use a slight delay for more dramtic zooming
    [self performSelector:@selector(addPin) withObject:nil afterDelay:0.5];
}

-(void)addPin{

    [self.mapView addAnnotation:self.pinView];
    [self.mapView selectAnnotation:self.pinView animated:YES];
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(self.coord, 800, 800);
    [self.mapView setRegion:[self.mapView regionThatFits:region] animated:YES];

}

-(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotationPoint
{
    if ([annotationPoint isKindOfClass:[MKUserLocation class]])//keep the user as default
        return nil;

    static NSString *annotationIdentifier = @"annotationIdentifier";
    MKPinAnnotationView *pinView = [[MKPinAnnotationView alloc]initWithAnnotation:annotationPoint reuseIdentifier:annotationIdentifier];
    pinView.pinColor = MKPinAnnotationColorPurple;
    //now we can throw an image in there

    return pinView;
}

I tried setting the title property for MKPinAnnotation but there isn't one. Is there anyway I can get around this?

回答1:

In viewForAnnotation, you need to set canShowCallout to YES (it's NO by default):

pinView.pinColor = MKPinAnnotationColorPurple;
pinView.canShowCallout = YES;

A couple of unrelated points:

It looks like you have a property named pinView of type MKPointAnnotation that you are using to create the annotation object in viewDidLoad. Then in viewForAnnotation, you have a local variable also named pinView of type MKPinAnnotationView. Although there is no naming conflict here, it causes and implies some conceptual confusion. MKPointAnnotation is an annotation model class while MKPinAnnotationView is an annotation view class -- they are completely different things. It would be better to name the annotation property pin or userAnnotation for example.
This comment in viewForAnnotation:
```
//now we can throw an image in there
```
seems to imply that you could set a custom image in the view at this point. Setting a custom image in a MKPinAnnotationView is not recommended since that class is designed to display default pin images in one of three colors. To use a custom image, create a plain MKAnnotationView instead.

回答2:

The pinColor property was deprecated in iOS 9. From iOS 9 onwards you should use pinTintColor which takes a UIColor rather than a MKPinAnnotationColor.

Old: MKPinAnnotationView *view = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:nil]; view.pinColor = MKPinAnnotationColorPurple;

New: MKPinAnnotationView *view = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:nil]; view.pinTintColor = [UI Color purpleColor];

There is more information available in the Apple docs.

回答3:

I just upgrade to ios 10, apple changed the api.

pinColor no longer in use, instead, use tintColor

New:

 MKPinAnnotationView *view = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:nil];
 view.tintColor = [UIColor purpleColor];

回答4:

Note that the pin title will be displayed when the user taps it:

If the value of this property is true, a standard callout bubble is shown when the user taps a selected annotation view. The callout uses the title and subtitle text from the associated annotation object. ( https://developer.apple.com/documentation/mapkit/mkannotationview/1452451-canshowcallout )

来源：https://stackoverflow.com/questions/29315590/trying-to-change-mkpointannotation-colour-but-losing-the-title

标签

ios

objective-c

mkpinannotationview