Sending nil to CGPoint type parameter

Question

Suppose I have this method:

- (void)placeView:(UIView*)theView withCenterIn:(CGPoint)centerPoint;

So I pass the view and a point to te the

Answer 1

You can't use nil as a "no point" indicator, because it is only for objects, and CGPoint is a struct. (As dasblinkenlight has already said.)

In my geometry library, I've defined a "null" CGPoint to use as a "no point" placeholder, and a function to test for it. Since the components of a CGPoint are CGFloats, and floats have a "invalid value" representation already -- NAN, defined in math.h -- I think that's the best thing to use:

// Get NAN definition
#include 

const CGPoint WSSCGPointNull = {(CGFloat)NAN, (CGFloat)NAN};

BOOL WSSCGPointIsNull( CGPoint point ){
    return isnan(point.x) && isnan(point.y);
}