Receiving errors when trying to draw with UIBezierPath

Question

Hello, I'm trying to draw some lines inside my custom UIView.

From what I can see, to save messing around with CoreGraphics, I can use UIBezierPath (i've done similar with NSBezierPath on the Mac). I have some code that tries to draw the lines but I get output errors and can't find a decent reference with some sample code to illustrate whats going on, any ideas? Code below...

Code:

  - (void)drawRect:(CGRect)rect {
    // Drawing code
    UIBezierPath *line1 = [UIBezierPath bezierPath];
 [[UIColor blackColor] setStroke];
 [line1 setLineWidth:3];
 [line1 moveToPoint:CGPointMake(0, 0)];
 [line1 addLineToPoint:CGPointMake(320, 480)];
 [line1 stroke];

}

Errors:

Sat Oct  2 19:26:43 mercury.config mobileManual[46994] <Error>: CGContextSetStrokeColorWithColor: invalid context 0x0

UPDATE: Here's the current code, No errors but also no drawing.. ideas?

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view setBackgroundColor:[UIColor yellowColor]];
    [self.view setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect {
    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    CGContextSaveGState(context);
    UIBezierPath *line1 = [UIBezierPath bezierPath];
    [line1 setLineWidth:3];
    [line1 moveToPoint:CGPointMake(0, 0)];
    [line1 addLineToPoint:CGPointMake(320, 480)];
    [line1 stroke];
    CGContextRestoreGState(context);
}

Answer 1

Your graphics context is invalid. This happens because:

• You called drawRect: yourself. Never do that. Call setNeedsDisplay instead and have iOS call it.
• You somehow destroyed the current graphics context (less likely).

Answer 2

Like I said above, your code is working fine for me.

Are you changing the "Class Identity" of the view in Interface Builder to your UIView subclass?

(As an aside, calling setNeedsDisplay in viewDidLoad is unnecessary, but it's also not hurting anything.)