I've a MKMapView. I want to put a custom MKAnnotation on my map.

They are some restaurant places. How can I do it?

My question is how can I make a c开发者_C百科ustom MKAnnotation?

Thanks, guys.

First, let's define custom as meaning not simply title and subtitle. We want to change the size of the MKAnnotation and include some custom graphics.

There are two parts to an annotation you might want to customize:

• MKAnnotation
• MKAnnotationView

For the most basic MKAnnotation you would simply adopt the protocol and return nil for title and subtitle, but you could also carry a lot more information in your annotation for an extended callout upon tapping an accessory indicator. You can add all of the annotations to the MKMapView using addAnnotation: in viewDidLoad for example.

MKAnnotation Header

@interface CPAnnotation : NSObject <MKAnnotation> {
@private
    CLLocationCoordinate2D _coordinate;
    NSString *_title;
    NSString *_subtitle;
}

@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
@property (nonatomic, readonly, copy) NSString *title;
@property (nonatomic, readonly, copy) NSString *subtitle;

- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate;
@end

MKAnnotation Implementation

@implementation CPAnnotation
@synthesize coordinate = _coordinate;
@synthesize title = _title;
@synthesize subtitle = _subtitle;

- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate {
    self = [super init];

    if (self != nil) {
        self.coordinate = coordinate;
    }

    return self;
}

- (NSString *)title {
    return _title;
}

- (NSString *)subtitle {
    return _subtitle;
}
@end

The next step is to customize the callout from the pin dropped. To do this you need to customize MKAnnotationView. According to Apple you shouldn't make a huge callout by default. They recommend a standard size callout that has a button to open a bigger one. They use the lowercase i in a blue circle icon. Those icons can be set via the view's leftCalloutAccessoryView and rightCalloutAccessoryView property. If you already adopted the MKMapViewDelegate protocol and set yourself as the MKMapView's delegate you will get the callback for viewForAnnotation:.

MKAnnotationView MKMapViewDelegate callback

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {
static NSString *const kAnnotationReuseIdentifier = @"CPAnnotationView";

MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:kAnnotationReuseIdentifier];
if (annotationView == nil) {
    annotationView = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:kAnnotationReuseIdentifier] autorelease];
    annotationView.enabled = YES;
    annotationView.canShowCallout = YES;
    annotationView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeInfoLight];
}

return annotationView;
}

You can further customize this in a custom view overriding the drawRect method, providing an image to the image property, or you could even implement an MKAnnotationView in a XIB. It is worth some experimentation.

Apple's WeatherAnnotationView Example illustrates overriding drawRect.

I had a case where I wanted something like a standard Pin annotation, but the designer wanted a custom graphic.

I wrote a subclass of MKAnnotationView to display the graphic. The only difference is that it overrides the standard class's image.

BlipAnnotationView.h

#import <MapKit/MapKit.h>

@interface BlipAnnotationView : MKAnnotationView

- (id)initWithAnnotation:(id<MKAnnotation>)annotation reuseIdentifier:(NSString *)reuseIdentifier;

@end

BlipAnnotationView.m

#import "BlipAnnotationView.h"

@implementation BlipAnnotationView

- (id)initWithAnnotation:(id<MKAnnotation>)annotation reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithAnnotation:annotation reuseIdentifier:reuseIdentifier];
    if (self) {
        UIImage *blipImage = [UIImage imageNamed:@"blip.png"];
        CGRect frame = [self frame];
        frame.size = [blipImage size];
        [self setFrame:frame];
        [self setCenterOffset:CGPointMake(0.0, -7.0)];
        [self setImage:blipImage];
    }
    return self;
}

@end

Then in the class that displays the map, I made the class implement the MKMapViewDelegate protocol. The mapView:viewForAnnotation: method creates a new instance of BlipAnnotationView if necessary.

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
    NSLog(@"mapView:%@ viewForAnnotation:%@", mapView, annotation);
    static NSString *const kAnnotationIdentifier = @"BlipMapAnnotation";
    BlipAnnotationView *annotationView = (BlipAnnotationView *)
    [mapView dequeueReusableAnnotationViewWithIdentifier:kAnnotationIdentifier];
    if (! annotationView) {
        annotationView = [[BlipAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:kAnnotationIdentifier];
    }
    [annotationView setAnnotation:annotation];

    return annotationView;
}

Finally I set the class as the delegate of the map view in awakeFromNib:

- (void)awakeFromNib
{
    [...]
    [_theMapView setDelegate:self];
}

I didn't have to change the code that positioned the annotation at all:

MKPointAnnotation *annotationPoint = [[MKPointAnnotation alloc] init];
[annotationPoint setCoordinate:[userLocation coordinate]];
[annotationPoint setTitle:label];
[_theMapView addAnnotation:annotationPoint];