iOS - MKMapView showAnnotations:animated: with pad

问题:

I want to be able to zoom my MKMapView to fit it's annotations. I have managed to do it using iOS7's showAnnotations method. But I would also like to add some padding or inset from the map view border. This is because I have a semi-transperant view that overlays the top part of my map, and I don't want annotations to be places behind this view. I have tried this:

[self.mapView showAnnotations:annotations animated:YES];
[self.mapView setVisibleMapRect:self.mapView.visibleMapRect edgePadding:UIEdgeInsetsMake(100, 20, 10, 10) animated:NO];

But it's not working as I would have hoped. Any ideas on how I could do it differently?

回答1:

You are doing it the right way. Try changing the padding, you'll see the difference.

Other way, there must be something else in your code preventing from changing the view

EDIT: I was totally wrong. Try this:

Create an instance variable

BOOL _mapNeedsPadding;

and initialize it to NO;

Then set your mapView delegate to self and add a to your class header

Then add this to your class

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated{
    if(_mapNeedsPadding){
        _mapNeedsPadding = NO;
        [self.mapView setVisibleMapRect:self.mapView.visibleMapRect edgePadding:UIEdgeInsetsMake(100, 20, 10, 10) animated:YES];
    }
}

And finally call your showAnnotations function like this:

_mapNeedsPadding = YES;
[self.mapView showAnnotations:annotations animated:YES];

The showAnnimation will trigger the regionDidChangeAnimated function. You need to set _mapNeedsPadding to NO after changing visibleMapRect because this function (setVisibleMapRect:self) will also trigger regionDidChangeAnimated.

Hope this helps !

回答2:

You could also simply use

[self.mapView showAnnotations:annotations animated:YES];
self.mapView.camera.altitude *= 1.4;

to zoom out a little. Works well for me.

回答3:

Starting with iOS8, MKMapView has a layoutMargin property. When this is set, centerRegion:, showAnnotations: and all methods that try to fit a rectangle within the map view will take into account the aforementioned layout margins.

If your translucent view is 40 points height and attached to the top of the map view, settings mapView.layoutMargin = UIEdgeInsetMake(40, 0, 0, 0) will do the magic.

If targeting iOS7, the map view uses the top and bottom layout guide of its containing controller to also offset its content. So you could override the topLayoutGuide method of the controller to return the desired length.

class ViewController: UIViewController {
      override var topLayoutGuide: UILayoutSupport {
        return MapLayoutGuide(length: 40)
    }
}


class MapLayoutGuide: NSObject, UILayoutSupport {
    var length: CGFloat

    init(length: CGFloat) {
        self.length = length
        super.init()
    }

    @available(iOS 9.0, *)
    var bottomAnchor: NSLayoutYAxisAnchor {
        return NSLayoutYAxisAnchor()
    }
    @available(iOS 9.0, *)
    var topAnchor: NSLayoutYAxisAnchor {
        return NSLayoutYAxisAnchor()
    }
    @available(iOS 9.0, *)
    var heightAnchor: NSLayoutDimension {
        return NSLayoutDimension()
    }
}

回答4:

another solution:

extension MKMapView
{
    func fitAllMarkers(inset: UIEdgeInsets? = nil) {
        self.showAnnotations(self.annotations, animated: false)
        OperationQueue.main.addOperation {
            self.setVisibleMapRect(self.visibleMapRect, edgePadding: inset ?? UIEdgeInsets.zero, animated: true)
        }
    }
}