How to override draw method on PDFAnnotation IOS-PDFKIT - objective-c

Question

I followed another StackOverflow post that explains how i could override the draw method of a PDFAnnotation so i could draw a picture instead of a traditional PDFAnnotation.
But sadly i was not able to achieve that and the annotation that is drawn on top of my pdf is still a regular one.
This is the code that i used :
#implementation PDFImageAnnotation { UIImage * _picture;
CGRect _bounds;};
-(instancetype)initWithPicture:(nonnull UIImage *)picture bounds:(CGRect) bounds{
self = [super initWithBounds:bounds
forType:PDFAnnotationSubtypeWidget
withProperties:nil];
if(self){
_picture = picture;
_bounds = bounds;
}
return self;
}
- (void)drawWithBox:(PDFDisplayBox) box
inContext:(CGContextRef)context {
[super drawWithBox:box inContext:context];
[_picture drawInRect:_bounds];
CGContextRestoreGState(context);
UIGraphicsPushContext(context);
};
#end
Does someone know how i could override the draw method so i could draw a custom Annotation ?
Thank You !
ps: i also tried to followed the tutorial on the apple dev site.
UPDATE :
Now i'm able to draw pictures using CGContextDrawImage but i'm not able to flip coordinates back in place. when i do that mi pictures are not drawn and it seems that they are put outside of the page but i'm not sure.
This is my new code :
- (void)drawWithBox:(PDFDisplayBox) box
inContext:(CGContextRef)context {
[super drawWithBox:box inContext:context];
UIGraphicsPushContext(context);
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, _pdfView.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, _bounds, _picture.CGImage);
CGContextRestoreGState(context);
UIGraphicsPopContext();
}

Answer 1

I also tried to follow the tutorial on the Apple dev site.
Which one?
Custom Graphics
Adding Custom Graphics to a PDF
Because both include UIGraphicsPushContext(context) & CGContextSaveGState(context) calls, but your code doesn't. Do not blindly copy & paste examples, try to understand them. Read what these two calls do.
Fixed code:
- (void)drawWithBox:(PDFDisplayBox) box
inContext:(CGContextRef)context {
[super drawWithBox:box inContext:context];
UIGraphicsPushContext(context);
CGContextSaveGState(context);
[_picture drawInRect:_bounds];
CGContextRestoreGState(context);
UIGraphicsPopContext();
}
The image was drawn with CGRectMake(20, 20, 100, 100). It's upside down, because PDFPage coordinates are flipped (0, 0 = bottom/left). Leaving it as an exercise for OP.
Rotation
Your rotation code is wrong:
CGContextTranslateCTM(context, 0.0, _pdfView.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, _bounds, _picture.CGImage);
It's based on _pdfView bounds, but it should be based on the image bounds (_bounds). Here's the correct one:
- (void)drawWithBox:(PDFDisplayBox) box
inContext:(CGContextRef)context {
[super drawWithBox:box inContext:context];
UIGraphicsPushContext(context);
CGContextSaveGState(context);
CGContextTranslateCTM(context, _bounds.origin.x, _bounds.origin.y + _bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
[_picture drawInRect:CGRectMake(0, 0, _bounds.size.width, _bounds.size.height)];
CGContextRestoreGState(context);
UIGraphicsPopContext();
}