My goal is to make a program that will draw points whenever the screen is touched. This is what I have so far:

The header file:

#import <UIKit/UIKit.h>


@interface ElSimView : UIView 
{
  CGPoint firstTouch;
  CGPoint lastTouch;
  UIColor *pointColor;
  CGRect *points;
  int npoints;
}

@property CGPoint firstTouch;
@property CGPoint lastTouch;
@property (nonatomic, retain) UIColor *pointColor;
@property CGRect *points;
@property int npoints;

@end

The implementation file:

//@synths etc.

- (id)initWithFrame:(CGRect)frame 
{
    return self;
}


- (id)initWithCoder:(NSCoder *)coder
{
  if(self = [super initWithCoder:coder])
  {
    self.npoints = 0;
  }
  return self;
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  UITouch *touch = [touches anyObject];
  firstTouch = [touch locationInView:self];
  lastTouch = [touch locationInView:self];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
  UITouch *touch = [touches anyObject];
  lastTouch = [touch locationInView:self];  
  points = (CGRect *)malloc(sizeof(CGRect) * ++npoints);
  points[npoints-1] = CGRectMake(lastTouch.x-15, lastTouch.y-15,30,30);
  [self setNeedsDisplay];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
  UITouch *touch = [touches anyObject];
  lastTouch = [touch locationInView:self];  
  [self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect 
{
  CGContextRef context = UIGraphicsGetCurrentContext();

  CGContextSetLineWidth(context, 2.0);
  CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);
  CGContextSetFillColorWithColor(context, pointColor.CGColor);

  for(int i=0; i<npoints; i++)
    CGContextAddEllipseInRect(context, points[i]);
  CGContextDrawPath(context, kCGPathFillStroke);
}


- (void)dealloc {
    free(points);
    [super dealloc];
}


@end

When I load this and click some points, it draws the first points normally, then then next points are drawn along with random ellipses (not even circles).

Also I have another question: When is exactly drawRect executed?