如何在Objective-C中更改方法分配表？

Question

As a practical example, in UIView, drawRect is called when setNeedsDisplay is set. I want a different drawRect routine to be called for the first time vs. the subsequent update. So for example, I want drawRect to call drawRectFirstTime for the first time and drawRect to call drawRectSubsequentUpdate for subsequent setNeedsDisplay.

How should this be done in Objective-C?

Answer 1

From top of my head:

- (void)drawRect:(NSRect)rect
{
   static BOOL first = YES;
   if (first == NO)
   {
      [self drawRectSubsequentUpdate:rect];
   } else {
      [self drawRectFirstTime:rect];
      first = NO
   }
}