CGContextAddEllipseInRect does not draw anything

Question

I´m trying to draw a circle with a number inside of it:

   -(void)drawRect:(CGRect)rect {
    //Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetLineWidth(context, 4.0);
    CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);
    CGContextBeginPath(context);
    CGContextAddEllipseInRect(context, rect);
    CGContextDrawPath(context, kCGPathFillStroke);

    // Label and index code
    UILabel* circleLabel = [[UILabel alloc] init];
    NSString *i=[Index stringValue];
    [circleLabel setText:i];
    [self addSubview:circleLabel];




}

I call the drawRect method from my own method:

-(void)addPhotoIndex:(NSNumber*)tempNumber withCoordinate:(NSString*)currentTouchPos{
    self.coord= CGPointFromString(currentTouchPos);
    CGRect rect= CGRectMake ((coord.x - 5), (coord.y- 5), 5, 5);
    NSNumber *Index= tempNumber;
    [self drawRect:rect];




}

That it is itself called from the ViewController.

But this is not drawing nothing, nor giving any errors. Can somebody help me please?

SOLUTION:

At the end, this is what it worked:

  -(void)addPhotoIndex:(NSNumber*)tempNumber withCoordinate:(NSString*)currentTouchPos{

    self.coord= CGPointFromString(currentTouchPos);
    CGRect rect= CGRectMake ((coord.x - 3), (coord.y- 3), 3, 3);
    NSNumber *Index= tempNumber;
    NSString *i=[Index stringValue];
    UIFont *font = [UIFont systemFontOfSize:15.0];

    // Drawing Point
    UIGraphicsBeginImageContext(self.frame.size);
    [self.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetLineWidth(context, 3.0);
    CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);
    CGContextBeginPath(context);
    CGContextAddEllipseInRect(context, rect);
    CGContextDrawPath(context, kCGPathFillStroke);
    [ i drawAtPoint:self.coord withFont:font];
    self.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();


}

A point with the index number are drawn next to each other in the correct position :) Thanks for your useful help!

Answer 1

The method you should be using is drawRect: not drawInRect:.

You also do not need to create your own context as this is set up for you in drawRect:

- (void)drawRect:(CGRect)rect;
{
  // UIGraphicsBeginImageContext(self.bounds.size); <-- not needed
  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextSetLineWidth(context, 4.0);
  CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);
  CGContextBeginPath(context);
  CGContextAddEllipseInRect(context, rect);
  CGContextDrawPath(context, kCGPathFillStroke); // Or kCGPathFill

  /*
   * As @Jonathan Cichon points out you should not add subview's here
   * either add them elsewhere or draw the string manually
   */
  // UILabel* circleLabel = [[UILabel alloc] init];
  // NSString *i=[Index stringValue];
  // [circleLabel setText:i];
  // [self addSubview:circleLabel];
  // UIGraphicsEndImageContext(); <-- not needed
}

Answer 2

I assume you implementated - (void)drawInRect:(CGRect)rect in a subclass of UIView. If so use - (void)drawRect:(CGRect)rect, so the context for drawing is already allocated when your method is called. Remove the UIGraphicsBeginImageContext and UIGraphicsEndImageContext calles. Also you should not add a subview in drawRect, use [i drawInRect:withFont:] instead