iphoneobjective-cmkmapviewoverlaymkoverlay

Draw text in circle overlay

I'm trying to draw some circle overlays containing text on MKMapView. I have subclassed the MKCircleView, in which I put the following (based on this), but the text does not appear. The circles show up correctly. (Also tried the first response's solution, same result).

-(void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context {
   [super drawMapRect:mapRect zoomScale:zoomScale inContext:context];
   NSString * t= @"XXXXX\nXXXX" ;
   UIGraphicsPushContext(context);
   CGContextSaveGState(context); 
   [[UIColor redColor] set];
   CGRect overallCGRect = [self rectForMapRect:[self.overlay boundingMapRect]];
   NSLog(@"MKC :  %lf, %lf ----> %lf , %lf ", mapRect.origin.x ,mapRect.origin.y , overallCGRect.origin.x, overallCGRect.origin.y);
   [t drawInRect:overallCGRect withFont:[UIFont fontWithName:@"Arial" size:10.0] lineBreakMode:UILineBreakModeClip alignment:UITextAlignmentCenter];
   CGContextRestoreGState(context);
   UIGraphicsPopContext();
}

When debugging, I get values like these

MKC :  43253760.000000, 104071168.000000 ----> 1.776503 , 1.999245 
MKC :  43253760.000000, 104071168.000000 ----> -1.562442 , -2.043090

Are they normal ? What am I missing ?

Thanks.

Solution

  • I believe your code is working and the problem is that the text is not being scaled properly making it invisible.

    Scale the font size based on the zoomScale using the MKRoadWidthAtZoomScale function:

    [t drawInRect:overallCGRect withFont:[UIFont fontWithName:@"Arial" 
    size:(10.0 * MKRoadWidthAtZoomScale(zoomScale))] 
    lineBreakMode:UILineBreakModeClip alignment:UITextAlignmentCenter];

    Also be sure to use a text color that's different from the underlying circle's color.

    Note that using drawInRect will result in the text being restricted to inside the circle and may get truncated. If you want to always show all the text, you could use drawAtPoint instead.