Question

I have a mapkit / view and it works fine – but I scroll around and after 2 – 10 moves my app crashed… and this only with a “interrupted”.

Here is part of my code. I think it’s a problem with the background threads and an array release / override problem.

Some background info: I generate a “session” key (MapKey) on mapview startup and save on the serverside a pin. The XML includes only new pins for a faster response and shorter XML.

// Update map when the user interacts with it
- (void)mapView:(MKMapView *)aMapView regionDidChangeAnimated:(BOOL)animated
{
    MyAnnotation *annotation = [[MyAnnotation alloc] init];
    MyAnnotation *ann = [[MyAnnotation alloc] init];
    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    NSString *postBody = [[[NSString alloc] initWithFormat:@"single=0&lat=%f&lng=%f&sid=%@",  mapView.centerCoordinate.latitude, mapView.centerCoordinate.longitude, [prefs stringForKey:@"MapKey"], [prefs stringForKey:@"MapKey"]] autorelease];
    [self performSelectorInBackground:@selector(getMark:) withObject:postBody];
}
// make post and interact with verarbeiten
-(void) getMark:(NSString *)postBody 
{
    NSAutoreleasePool *ccpool = [[NSAutoreleasePool alloc] init];
    NSString *urlStr = [[[NSString alloc] initWithFormat:@"http://URL/get.php"] autorelease];
    NSMutableURLRequest *request;
    NSData *postData = [postBody dataUsingEncoding:NSUTF8StringEncoding];
    NSError *error;
    NSURLResponse *response;
    NSData *dataReply;
    id stringReply;

    request = [NSMutableURLRequest requestWithURL: [NSURL URLWithString:urlStr]];

    [request setHTTPMethod: @"POST"];
    [request setHTTPBody:postData];
    [request setValue:@"text/xml" forHTTPHeaderField:@"Accept"];

    dataReply = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    stringReply = (NSString *)[[[NSString alloc] initWithData:dataReply encoding:NSUTF8StringEncoding] autorelease];
    [self performSelectorInBackground:@selector(verarbeiten:) withObject:stringReply];

    [ccpool release];
}

//generate annotations array with annotations an set it to mapview
-(void) verarbeiten:(NSString *)stringReply 
{
    NSAutoreleasePool *bbpool = [[NSAutoreleasePool alloc] init];
    CXMLDocument *rssParser = [[[CXMLDocument alloc] initWithXMLString:stringReply options:0 error:nil] autorelease];
    NSMutableArray* annotations = [[NSMutableArray alloc] init];
    NSArray *resultNodes = nil;
    resultNodes = nil;
    resultNodes = [rssParser nodesForXPath:@"//place" error:nil];
    for (CXMLElement *resultElement in resultNodes) 
    {
        MyAnnotation *ann = [[MyAnnotation alloc] init];
        ann.title = [[resultElement childAtIndex:3] stringValue];
        ann.subtitle = [[resultElement childAtIndex:5] stringValue];
        ann.currentPoint = [NSNumber numberWithInt:[[[resultElement childAtIndex:1] stringValue] intValue]]; 
        MKCoordinateRegion region = { {0.0, 0.0 }, { 0.0, 0.0 } };
        region.center.latitude = [[[resultElement childAtIndex:9] stringValue] floatValue];
        region.center.longitude = [[[resultElement childAtIndex:7] stringValue] floatValue];
        ann.coordinate = region.center;
        //[mapView addAnnotation:ann ];

        [annotations addObject:ann];
    }
    [mapView addAnnotations:annotations ];
    [annotations release];
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    [bbpool release];
}

- (MKAnnotationView *) mapView:(MKMapView *)mV viewForAnnotation:(MyAnnotation *) annotation 

{
    MKPinAnnotationView *pinView = nil;
    if(annotation != mapView.userLocation) 
    {
        static NSString *defaultPinID = @"de.my.pin";
        pinView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:defaultPinID];
        if ( pinView == nil )
            pinView = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:defaultPinID] autorelease];

        pinView.pinColor = MKPinAnnotationColorRed;
        pinView.canShowCallout = YES;
        pinView.animatesDrop = NO;
        pinView.userInteractionEnabled = YES;
        UIButton *btnVenue = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
        btnVenue.tag = [annotation.currentPoint intValue];
        [btnVenue addTarget:self action:@selector(showLinks:) forControlEvents:UIControlEventTouchUpInside];                                
        pinView.rightCalloutAccessoryView = btnVenue;
    }
    else
    {
        [mapView.userLocation setTitle:@"You are here"];
    }

    return pinView;
}



#import "MyAnnotation.h"


@implementation MyAnnotation

@synthesize coordinate, title, subtitle,currentPoint;

-(void)dealloc 
{
    [title release];
    [subtitle release];
    [super dealloc];
}

@end



#import <Foundation/Foundation.h>
#import <MapKit/MKAnnotation.h>

@interface MyAnnotation : NSObject <MKAnnotation> 
{
    CLLocationCoordinate2D coordinate;
    NSString *title;
    NSString *subtitle;
    NSNumber *currentPoint;
}

@property (nonatomic, assign) CLLocationCoordinate2D coordinate;
@property (nonatomic, copy) NSString *title;
@property (nonatomic, copy) NSString *subtitle;
@property(nonatomic, retain) NSNumber *currentPoint;

@end

Answer 1

Just a thought: since -[MKMapView addAnnotations:] (potentially) performs UI modifications, you may want to call it in the main thread:

[mapView performSelectorOnMainThread: @selector(addAnnotations:) withObject: annotations waitUntilDone: YES];