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POIssue with Annotation Views disappearing on double tap zoom
 

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  1. POIssue with Annotation Views disappearing on double tap zoom
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    <p>I've ran into a problem with annotation views in the MapKit on the iPhone. I manage to draw custom annotation views on the map - no problem there. I even manage to redraw them after dragging or zooming. However, there are cases where the redrawing does not work: an example would be double-tap zoom.</p> <p>I attach some code where I draw a few rectangles at specific locations on the map, and when I zoom using a two finger gesture, everything works fine (i.e. the rectangles are redrawn). However, when I double tap, the rectangles disappear. What's even stranger is that all methods get called in the order that they should, and in the end, even the drawRect gets called - but the rectangles are not drawn.</p> <p>So here's the code, please try for yourself - two finger zooming works, but double-tap zooming doesn't:</p> <p>PlaygroundViewController.h</p> <pre><code>#import &lt;UIKit/UIKit.h&gt; #import &lt;MapKit/MapKit.h&gt; @interface PlaygroundViewController : UIViewController &lt;MKMapViewDelegate&gt;{ MKMapView *mapView_; NSMutableDictionary* myViews_; } @end </code></pre> <p>PlaygroundViewController.m</p> <pre><code>#import "PlaygroundViewController.h" #import "Territory.h" #import "TerritoryView.h" @implementation PlaygroundViewController - (void)viewDidLoad { [super viewDidLoad]; mapView_=[[MKMapView alloc] initWithFrame:self.view.bounds]; [self.view insertSubview:mapView_ atIndex:0]; mapView_.delegate = self; [mapView_ setMapType:MKMapTypeStandard]; [mapView_ setZoomEnabled:YES]; [mapView_ setScrollEnabled:YES]; myViews_ = [[NSMutableDictionary alloc] init]; for (int i = 0; i &lt; 10; i++ ) { Territory *territory; territory = [[[Territory alloc] init] autorelease]; territory.latitude_ = 40 + i; territory.longitude_ = -122 + i; [mapView_ addAnnotation:territory]; } } - (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id &lt;MKAnnotation&gt;)annotation { MKAnnotationView* territoryView = (MKAnnotationView*)[mapView dequeueReusableAnnotationViewWithIdentifier:@"Territory"]; if (!territoryView){ territoryView = [[[TerritoryView alloc] initWithAnnotation:annotation reuseIdentifier:@"Territory"] autorelease]; Territory* currentTerritory = (Territory*) annotation; [myViews_ setObject:territoryView forKey:currentTerritory.territoryID_]; } else{ territoryView.annotation = annotation; } return territoryView; } - (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated { for (NSObject* key in [myViews_ allKeys]) { TerritoryView* territoryView = [myViews_ objectForKey:key]; [territoryView initRedraw]; } } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } - (void)dealloc { [super dealloc]; } </code></pre> <p>Territory.h</p> <pre><code>#import &lt;Foundation/Foundation.h&gt; #import &lt;MapKit/MapKit.h&gt; @interface Territory : NSObject &lt;MKAnnotation&gt; { float latitude_; float longitude_; NSString* territoryID_; } @property (nonatomic) float latitude_; @property (nonatomic) float longitude_; @property (nonatomic, retain) NSString* territoryID_; @end </code></pre> <p>Territory.m</p> <pre><code>#import "Territory.h" @implementation Territory @synthesize latitude_; @synthesize longitude_; @synthesize territoryID_; - (CLLocationCoordinate2D)coordinate { CLLocationCoordinate2D coord_ = {self.latitude_, self.longitude_}; return coord_; } -(id) init { if (self = [super init]) { self.territoryID_ = [NSString stringWithFormat:@"%p", self]; } return self; } @end </code></pre> <p>TerritoryView.h</p> <pre><code>#import &lt;Foundation/Foundation.h&gt; #import &lt;MapKit/MapKit.h&gt; @interface TerritoryView : MKAnnotationView { } - (id)initWithAnnotation:(id &lt;MKAnnotation&gt;)annotation reuseIdentifier:(NSString *)reuseIdentifier; - (void)initRedraw; @end </code></pre> <p>TerritoryView.m</p> <pre><code>#import "TerritoryView.h" @implementation TerritoryView - (id)initWithAnnotation:(id &lt;MKAnnotation&gt;)annotation reuseIdentifier:(NSString *)reuseIdentifier { if ([super initWithAnnotation:annotation reuseIdentifier:@"Territory"]) { self.initRedraw; } return self; } - (void)initRedraw { self.frame = CGRectMake(0,0,40,40); [self setNeedsDisplay]; } - (void)drawRect:(CGRect)rect { NSLog(@"in draw rect"); } @end </code></pre> <p>Any help is appreciated. Here's the zipped project: <a href="http://www.salathe.com/docroot/Playground.zip" rel="nofollow noreferrer">link</a></p>
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