custom map annotation callout - how to control width - ios

Question

I've successfully implemented the custom map annotation callout code from the asynchrony blog post .
(When user taps a map pin, I show a customized image instead of the standard callout view).
The only remaining problem is that the callout occupies the entire width of the view, and the app would look much better if the width corresponded to the image I'm using.
I have subclassed MKAnnotationView, and when I set it's contentWidth to the width of the image, the triangle does not always point back to the pin, or the image is not even inside it's wrapper view.
Any help or suggestions would be great.
Thanks.

Answer 1

I ran into a similar problem when implementing the CalloutMapAnnotationView for the iPad. Basically I didn't want the iPad version to take the full width of the mapView.
In the prepareFrameSize method set your width:
- (void)prepareFrameSize {
// ...
// changing frame x/y origins here does nothing
frame.size = CGSizeMake(320.0f, height);
self.frame = frame;
}
Next you'll have to calculate the xOffset based off the parentAnnotationView:
- (void)prepareOffset {
// Base x calculations from center of parent view
CGPoint parentOrigin = [self.mapView convertPoint:self.parentAnnotationView.center
fromView:self.parentAnnotationView.superview];
CGFloat xOffset = 0;
CGFloat mapWidth = self.mapView.bounds.size.width;
CGFloat halfWidth = mapWidth / 2;
CGFloat x = parentOrigin.x + (320.0f / 2);
if( parentOrigin.x < halfWidth && x < 0 ) // left half of map
xOffset = -x;
else if( parentOrigin.x > halfWidth && x > mapWidth ) // right half of map
xOffset = -( x - mapWidth);
// yOffset calculation ...
}
Now in drawRect:(CGRect)rect before the callout bubble is drawn:
- (void)drawRect:(CGRect)rect {
// ...
// Calculate the carat lcation in the frame
if( self.centerOffset.x == 0.0f )
parentX = 320.0f / 2;
else if( self.centerOffset.x < 0.0f )
parentX = (320.0f / 2) + -self.centerOffset.x;
//...
}
Hope this helps put you on the right track.