Iphone SDK quesiton: How to make a Drawing method in a View class work using CGContextRef?

Question

I have these 2 methods in the View class. the drawRect method always gets called when the view is initalized. But i can't get the drawLine method to work. It doesn't do anything when it gets called. Am i supposed to deal with cgimagecontext or something like that? please help!!

- (void)drawRect:(CGRect)rect {
    // Drawing code
    // Drawing code
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    //CGContextSetRGBFillColor(contextRef, 0, 0, 255, 1);
    CGContextSetRGBStrokeColor(contextRef, 0, 0, 0, 1);
    CGContextSetLineWidth(contextRef, 5.0);
    CGContextBeginPath(contextRef);
    CGContextMoveToPoint(contextRef, 0, 0);
    CGContextAddLineToPoint(contextRef, 320, 480);
    CGContextStrokePath(contextRef);
}

    -(void)drawLine:(CGPoint)from to:(CGPoint) to {
    // Drawing code
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    //CGContextSetRGBFillColor(contextRef, 0, 0, 255, 1);
    CGContextSetRGBStrokeColor(contextRef, 0, 128, 0, 1);
    CGContextSetLineWidth(contextRef, 5.0);
    CGContextBeginPath(contextRef);
    CGContextMoveToPoint(contextRef, 0, 0);
    CGContextAddLineToPoint(contextRef, 320, 50);
    CGContextStrokePath(contextRef);

}

Answer 1

Are you calling -drawLine from within -drawRect? You need to do all drawing in a view within your drawRect method. If you're calling -drawLine from somewhere else, it won't work.

Answer 2

You can only do drawing in drawrect. If you want to draw custom lines via your drawLine method, replace the hard-coded points in drawrect with variables. You can then set these variables in your drawLine method and finally call [self setNeedsDisplay].