iOS7 - Map view pin do not appear until screen is touched

问题

In my app, I download a set of point from a web service using json. Actualizing the app to iOS7, I am experimenting that problem: the locations are downloaded but pins on the map are not painted until user touchs and "moves" the map. Then they appear and all work as in iOS6.

How can I correct that behavior?

EDIT: AddAnnotation is called at the end of a method that receive data, parse the json and pass them to mylocaction object:

- (void)plotBarPosition:(NSString *)data_string {
    // Parse the string into JSON
    NSDictionary *json = [(NSDictionary*)[datos_string1 JSONValue]objectForKey:@"features"];

    for (int i = 0; i < [json count]; i++){

      /*
      PARSING EACH POINT
      */

    MyLocation *location =[[MyLocation alloc] initWithName:nameLoc coordinate:coordinate estado:status antenaId:antenaId];

    [_mapView addAnnotation:location];
     }

}

I tryed also:

[_mapView performSelectorOnMainThread: @selector(addAnnotations:) withObject: location waitUntilDone: NO];

but in this case, annotations do not appear at all.

回答1:

As this answer and the comment by @RAJA suggest, call addAnnotation: or addAnnotations: on the main thread. You could do this using GCD or performSelectorOnMainThread.

The option with the least changes to your existing code is to call addAnnotation: (singular):

- (void)plotBarPosition:(NSString *)data_string {
    // Parse the string into JSON
    NSDictionary *json = [(NSDictionary*)[datos_string1 JSONValue]objectForKey:@"features"];

    for (int i = 0; i < [json count]; i++){

        /*
         PARSING EACH POINT
         */

        MyLocation *location =[[MyLocation alloc] initWithName:nameLoc coordinate:coordinate estado:status antenaId:antenaId];

        //[_mapView addAnnotation:location];
        [_mapView performSelectorOnMainThread:@selector(addAnnotation:) 
                                   withObject:location 
                                waitUntilDone:YES];
    }
}

Alternatively, to use addAnnotations: (plural), you first add your annotations to a local array and give them to the map view all together in a single call. Changes below are marked with >>>:

- (void)plotBarPosition:(NSString *)data_string {
    // Parse the string into JSON
    NSDictionary *json = [(NSDictionary*)[datos_string1 JSONValue]objectForKey:@"features"];

    //>>> initialize array to hold annotations...
    NSMutableArray *annotationsToAdd = [NSMutableArray array];

    for (int i = 0; i < [json count]; i++){

        /*
         PARSING EACH POINT
         */

        MyLocation *location =[[MyLocation alloc] initWithName:nameLoc coordinate:coordinate estado:status antenaId:antenaId];

        //>>> comment out direct addAnnotation...
        //[_mapView addAnnotation:location];

        //>>> add annotation to local array...
        [annotationsToAdd addObject:location];
    }

    //>>> call addAnnotations: (plural) on main thread...
    [_mapView performSelectorOnMainThread:@selector(addAnnotations:) 
                               withObject:annotationsToAdd 
                            waitUntilDone:YES];
}

回答2:

There is a protocol MKAnnotation - you have to determine you own class for annotation with realizing of this protocol:

@interface MyAnnotation : NSObject <MKAnnotation> {
    CLLocationCoordinate2D coordinate;
}

@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;

- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate;

Then you have to init MyAnnotation and add it on map:

MyAnnotation *annotation = [[MyAnnotation alloc] initWithCoordinate:CLLocationCoordinate2DMake(latitude, longitude)];
[myMap addAnnotation:annotation];

Also try to call

[mapView setNeedsDisplay];
or
[mapView setNeedsLayout];

after adding annotations

来源：https://stackoverflow.com/questions/21841225/ios7-map-view-pin-do-not-appear-until-screen-is-touched

标签

ios

ios7

mkmapview