Question

I made a UIViewController class. Displays fine. I then made a UIView class to use with it. In InterfaceBuilder, I set the UIView class to my own custom UIView class. I then overrode the drawRect method in that class:

- (void)drawRect:(CGRect)rect 
{
    NSLog(@"Yes we are drawing with width: %f", rect.size.width);

    CGContextRef g = UIGraphicsGetCurrentContext();
    CGContextSetRGBStrokeColor(g, 1, 1, 1, 1);
    CGContextSetRGBFillColor(g, 1, 1, 1, 0);
    CGContextFillRect(g, CGRectMake(0, 0, 100, 100));

and I can see that the log statement prints, however none of my drawing code actually has any visible effect. The rect does not get drawn on screen. Is there some other connection I had to make in InterfaceBuilder for this to work?

Other than setting the class name for the UIView property of my view controller in InterfaceBuilder, I haven’t changed anything else.

Thanks

Answer 1

The last argument to CGContextSetRGBFillColor is the alpha of the fill color. You’re setting it to zero, so you’re filling with a transparent color. Try this:

- (void)drawRect:(CGRect)rect 
{
    NSLog(@"Yes we are drawing with width: %f", rect.size.width);

    CGContextRef g = UIGraphicsGetCurrentContext();
    CGContextSetRGBStrokeColor(g, 1, 1, 1, 1);
    CGContextSetRGBFillColor(g, 1, 1, 1, 1);
    CGContextFillRect(g, CGRectMake(0, 0, 100, 100));
...