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POiphone mkannotationview strange problem - possibly being reused
 

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  1. POiphone mkannotationview strange problem - possibly being reused
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    <p>I've just found a strange issue with my sub classed mkannotationview.</p> <p>When I add the first 5 markers, they all work perfectly. In the mkannotationview sub class, I NSLog a message which I see 5 times. However, when I remove ALL the markers and redraw them - using all the same methods, I see the NSLog only once. </p> <p>It's like the map is reusing existing annotationviews? Is there a way to force it to use new ones each time? </p> <p>[UPDATE with code]</p> <p>So the reason I cannot reuse (and this may or may not be the problem) is that I am creating unique markers with a label. The label on the marker contains a reference to the individual marker (consider it like a product ID)</p> <p>So... in ProductPlot.h</p> <pre><code>@interface ProductPlot : NSObject &lt;MKAnnotation&gt; { NSString *productID; float latitude; float longitude; } @property (nonatomic, copy) NSString *productID; </code></pre> <p>and ProductPlot.m</p> <pre><code>@implementation ProductPlot @synthesize productID; - (CLLocationCoordinate2D)coordinate { CLLocationCoordinate2D coord = {self.latitude, self.longitude}; return coord; } - (NSString *) productID { return productID; } </code></pre> <p>then I have the annotation view sub classed as ProductPlotView.h</p> <pre><code>@interface ProductPlotView : MKAnnotationView { ProductPlot *product; } </code></pre> <p>and in ProductPlotView.m</p> <pre><code>@implementation ProductPlotView - (id)initWithAnnotation:(id &lt;MKAnnotation&gt;)annotation reuseIdentifier:(NSString *)reuseIdentifier { if(self = [super initWithAnnotation:annotation reuseIdentifier:reuseIdentifier]) { product = (ProductPlot *)annotation; UILabel *plate2 = [[[UILabel alloc] init] autorelease]; plate2.text = product.productID; plate2.frame = CGRectMake(35, 4, 100, 30); plate2.backgroundColor = [UIColor clearColor]; //]clearColor]; [plate2 setFont: [UIFont fontWithName: @"myFont" size: plate2.font.pointSize]]; [self addSubview:plate2]; } self.frame = CGRectMake(0,0,133,40); return self; } </code></pre> <p>So then in my code, I plot the points using</p> <pre><code>- (void)plotPoint: (int) y latitude: (double) lat longitude: (double) lng productID: (NSString *) pID { ProductPlot *newAnnotation = [[ProductPlot alloc] init]; newAnnotation.latitude = lat; newAnnotation.longitude = lng; newAnnotation.productID = pID; [mapView addAnnotation:newAnnotation]; [newAnnotation release]; } </code></pre> <p>I also have the code to handle the annotations.</p> <pre><code>- (MKAnnotationView *)mapView:(MKMapView *)lmapView viewForAnnotation:(id &lt;MKAnnotation&gt;)annotation { ProductPlotView *eventView = (ProductPlotView *)[lmapView dequeueReusableAnnotationViewWithIdentifier:@"eventview"]; if(eventView == nil) { eventView = [[[VehicleViewInfo alloc] initWithAnnotation:annotation reuseIdentifier:@"eventview"] autorelease]; } eventView.annotation = annotation; return eventView; } </code></pre> <p>So... the above will take the productID and place it on a label which is the map marker. This seems to work perfectly on the FIRST plot instance, but if I remove the markers (using <code>[mapView removeAnnotations:mapView.annotations];</code>) then call this function again, it draws the points OK, but the product IDs are not correct. It appears to draw them at random. </p> <blockquote> <p>NOTE: the code above has had a few parts removed, so there may be typos</p> </blockquote> <p>Thanks for any info.</p>
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    1. USMatt Facer
    1. USMatt Facer
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      1. POiphone mkannotationview strange problem - possibly being reused
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    1. COWhy don't you post some sample code so we can help you. From a strategy perspective you should be leveraging a reuse queue just like you would in a tableview. Assuming a common design with different content- Why would you want to force new ones to be created each time? The idea is to avoid allocations and use the efficiency of a reuse queue. Chances are if you started with sample code or followed any of the documentation you will have been on this path.
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      1. POiphone mkannotationview strange problem - possibly being reused
      1. USNick
    2. COThanks Nick. I will post some code following this
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      1. USMatt Facer
 

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