MKMapView setRegion设置为小区域会导致卫星图像加载失败

Question

I have been working on the same app for a number of months, and this is a new problem. I am wondering if there has been a change in the server side of the Apple Map data. Here's the issue:

My app (at times) wants to set an MKMapView region to the most fully zoomed in value possible around a particular location. To do this, I do something like:

self.map.mapType = MKMapTypeHybrid;
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(CLLocationCoordinate2DMake(item.lat, item.lng), 1.0, 1.0);
[self.map setRegion:region animated:NO];

Regardless of where item's coordinate is, I get the gridded "no satellite images" background. This does not seem to be related to available satellite imagery, as it behaves consistently across many areas of the US.

I am aware that setRegion:animated: may adjust the region after the fact. And I am aware the a 1m square is an unreasonably small area to attempt to show on a fairly large map. So, I've tried

[self.map setRegion:[self.map regionsThatFits:region] animated:NO];

Setting animated:YES does seem to prevent this from occurring, but I do not want to animate these changes.

A few more observations:

• If I zoom out just 1 or 2 pixels, the map imagery appears.
• Attempting to implement the map delegate method: – mapViewDidFailLoadingMap:withError: does not help. It never is called.
• This seems to be new. The working version I have of the app in the app store, now exhibits similar issues.
• I have seen this happen in other popular apps recently.

Any thoughts on a solution to this, or confirmation that it is a systemic problem?

Answer 1

//fix for ios6
if (region.span.latitudeDelta < .0005f)
    region.span.latitudeDelta = .0005f;
if (!region.span.longitudeDelta < .0005f)
    region.span.longitudeDelta = .0005f;

Make sure your region span for lat/lon isn't set too low and it will clear up.

Answer 2

I ended up subclassing MKMapView and overriding setRegion: . I've created a sample app in Github if anyone is interested in seeing the issue in action, or my solution:

https://github.com/DeepFriedTwinkie/iOS6MapZoomIssue

My setRegion: method looks like this:

- (void) setRegion:(MKCoordinateRegion)region animated:(BOOL)animated {
    @try {
        // Get the zoom level for the proposed region
        double zoomLevel = [self getFineZoomLevelForRegion:region];

        // Check to see if any corrections are needed:
        //     - Zoom level is too big (a very small region)
        //     - We are looking at satellite imagery (Where the issue occurs)
        //     - We have turned on the zoom level protection

        if (zoomLevel >= (MAX_GOOGLE_LEVELS-1) && self.mapType != MKMapTypeStandard && self.protectZoomLevel) {
            NSLog(@"setRegion: Entered Protected Zoom Level");

            // Force the zoom level to be 19 (20 causes the issue)
            MKCoordinateRegion protectedRegion = [self coordinateRegionForZoomLevel:MAX_GOOGLE_LEVELS-1.0 atCoordinate:region.center];
            [super setRegion:protectedRegion animated:animated];
        } else {
            [super setRegion:region animated:animated];
        }
    }
    @catch (NSException *exception) {
        [self setCenterCoordinate:region.center];
    }
}