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POiOS - How to limit the MapView to a specific region?
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  1. POiOS - How to limit the MapView to a specific region?
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    copied!<p>I have the following problem:</p> <p>I have a "drawn map" (image) which I add to the MapView as an Overlay. No Problem with that.. but I need to limit the MapView to the region of the Overlay, so a user isn't able to scroll/zoom outside of this region.. but it should be possible to scroll/zoom inside the "bounds" of the overlay - means I cannot just disable zoom/scrolling for the MapView.</p> <p>Are there any ideas/solution on this topic? The reason for using the MapView/-Kit is that I need to add various POIs to the custom map. This may become more complex when just using an ImageView+ScrollView for presenting the custom map.</p> <p>I've researched alot on this topic, but I didn't found a nice solution.</p> <p>Any help is appreciated!</p> <p>Best Regards, Christian</p> <p><strong>Edit: This is our solution:</strong> <em>You supply a topleft and a bottomright coordinate to limit the map. The (minimum) zoomlevel is also limited. I've deactivated decelerating and you are able to bounce a bit out of the map (for better performance/ux). I added a ~1km grey border to the overlay so the user isnÄt able to see the orignal worldmap of google.</em></p> <p><strong>LimitedMapView.h:</strong></p> <pre><code>#import &lt;Foundation/Foundation.h&gt; #import &lt;MapKit/MapKit.h&gt; @interface LimitedMapView : MKMapView &lt;UIScrollViewDelegate&gt;{ } @property (nonatomic, assign) CLLocationCoordinate2D topLeftCoordinate; @property (nonatomic, assign) CLLocationCoordinate2D bottomRightCoordinate; @end </code></pre> <p><strong>LimitedMapView.m:</strong></p> <pre><code>#import "LimitedMapView.h" @implementation LimitedMapView @synthesize topLeftCoordinate, bottomRightCoordinate; - (void)scrollViewDidZoom:(UIScrollView *)scrollView{ if([super respondsToSelector:@selector(scrollViewDidZoom:)]) [super scrollViewDidZoom:scrollView]; if ([self region].span.latitudeDelta &gt; 0.002401f || [self region].span.longitudeDelta &gt; 0.003433f) { CLLocationCoordinate2D center = self.centerCoordinate; MKCoordinateSpan span = MKCoordinateSpanMake(0.002401f, 0.003433f); self.region = MKCoordinateRegionMake(center, span); } } -(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{ if([super respondsToSelector:@selector(scrollViewDidEndDragging:)]) [super scrollViewDidEndDragging:scrollView willDecelerate:decelerate]; MKCoordinateRegion currentRegion = self.region; bool changeRegionLong = YES; bool changeRegionLat = YES; // LONGITUDE if((currentRegion.center.longitude - (currentRegion.span.longitudeDelta/2)) &lt; self.topLeftCoordinate.longitude) { currentRegion.center.longitude = (topLeftCoordinate.longitude + (currentRegion.span.longitudeDelta/2)); } else if((currentRegion.center.longitude + (currentRegion.span.longitudeDelta/2)) &gt; self.bottomRightCoordinate.longitude) { currentRegion.center.longitude = (bottomRightCoordinate.longitude - (currentRegion.span.longitudeDelta/2)); } else { changeRegionLong = NO; } // LATITUDE if((currentRegion.center.latitude + (currentRegion.span.latitudeDelta/2)) &gt; self.topLeftCoordinate.latitude) { currentRegion.center.latitude = (topLeftCoordinate.latitude - (currentRegion.span.latitudeDelta/2)); } else if((currentRegion.center.latitude - (currentRegion.span.latitudeDelta/2)) &lt; self.bottomRightCoordinate.latitude) { currentRegion.center.latitude = (bottomRightCoordinate.latitude + (currentRegion.span.latitudeDelta/2)); } else { changeRegionLat = NO; } if(changeRegionLong || changeRegionLat) [self setRegion:currentRegion animated:YES]; } -(void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView{ [scrollView setContentOffset:scrollView.contentOffset animated:YES]; } @end </code></pre>
 

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