CODEWITHSUNDEEP
iosobjective-cmkmapview
LLooggaann
LLooggaann

Reputation: 455

Why isn't the center of my mapview's frame lining up its center coordinate?

I'm trying to render a circle at the center of a mapview. I'm also displaying the user's current location on the mapview, and setting the center of the map to there. These two are not lining up, though.

Here is where I set up my circle:

[self.mapView setShowsUserLocation:YES];
CAShapeLayer *circle = [CAShapeLayer layer];
int radius = 50;
circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 2.0*radius, 2.0*radius)
                                         cornerRadius:radius].CGPath;
// Set position of the circle.
// We use the frame of the mapview subtracted by circle radius to determine the center
circle.position = CGPointMake(CGRectGetMidX(self.mapView.frame)-radius,
                              CGRectGetMidY(self.mapView.frame)-radius);
circle.fillColor = [[UIColor alloc] initWithRed:0.5 green:0.5 blue:0.6 alpha:0.3].CGColor;
circle.strokeColor = [UIColor blackColor].CGColor;
circle.lineWidth = 1;

// Add to parent layer
[self.mapView.layer addSublayer:circle];

// Add 'crosshair'
UIView *view = [[UIView alloc] init];
view.backgroundColor = [UIColor blackColor];
view.frame = CGRectMake(0, 0, 5, 5);
[self.mapView addSubview:view];
view.center = self.mapView.center;

And in the didUpdateUserLocation delegate method I have:

    [self.mapView setCenterCoordinate:userLocation.coordinate];

Here's what it looks like on the simulator.

enter image description here

I eventually want to allow the user to pan and select a region of the map, but now I'm not sure if my centercoordinate of the map is even coinciding with the center of my circle. Any help? Thanks!

Upvotes: 4

Views: 384

Answers (4)

bcr
bcr

Reputation: 2073

Using Xamarin.Forms, I had to make sure to enable the Safe Area Layout Guide, adding this to my ContentPage XAML.

<ContentPage ...
         xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
         Title="Safe Area"
         ios:Page.UseSafeArea="true">
<StackLayout>
    ...
</StackLayout>

For more info: Safe Area Layout Guide on iOS

Upvotes: 0

NathanAldenSr
NathanAldenSr

Reputation: 7961

You may be running into the same bug I discovered recently. I have reported it to Apple and it was marked as a duplicate, so perhaps it'll be fixed in iOS 7.1.

Bug with MKMapView's centerCoordinate during rotation?

Upvotes: 1

ameguid12
ameguid12

Reputation: 13

I think It's a status bar issue.

Try this.

[self.mapView setShowsUserLocation:YES];
CAShapeLayer *circle = [CAShapeLayer layer];
int radius = 50;
circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 2.0*radius, 2.0*radius)
                                     cornerRadius:radius].CGPath;
// Set position of the circle.
// We use the frame of the mapview subtracted by circle radius to determine the center
circle.position = CGPointMake(CGRectGetMidX(self.mapView.frame)-radius,
                          CGRectGetMidY(self.mapView.frame)-radius-20);
circle.fillColor = [[UIColor alloc] initWithRed:0.5 green:0.5 blue:0.6 alpha:0.3].CGColor;
circle.strokeColor = [UIColor blackColor].CGColor;
circle.lineWidth = 1;

// Add to parent layer
[self.mapView.layer addSublayer:circle];

// Add 'crosshair'
UIView *view = [[UIView alloc] init];
view.backgroundColor = [UIColor blackColor];
view.frame = CGRectMake(0, 0, 5, 5);
[self.mapView addSubview:view];
view.center = self.mapView.center;

I hope it works with you.

Upvotes: 1

nevan king
nevan king

Reputation: 113777

Looks like a 20 point offset (same as the status bar). Perhaps your map view is being resized after you use the frame to find the center.

You might try using an MKCircleView or other overlays to do this instead of shape layers.

Upvotes: 0

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