DNCloseButton.h

//
//  DNCloseButton.h
//  ParkingMobility
//
//  Created by Michael Nachbaur on 10-08-22.
//  Copyright 2010 Decaf Ninja Software. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface DNCloseButton : UIButton {
}

@end

DNCloseButton.m

//
//  DNCloseButton.m
//  ParkingMobility
//
//  Created by Michael Nachbaur on 10-08-22.
//  Copyright 2010 Decaf Ninja Software. All rights reserved.
//

#import "DNCloseButton.h"

@implementation DNCloseButton

- (id)initWithFrame:(CGRect)frame {
    if ((self = [super initWithFrame:frame])) {
		CGFloat radius = self.bounds.size.width / 2;
		CGFloat borderWidth = self.bounds.size.width / 10;
		
		self.layer.backgroundColor = [[UIColor blackColor] CGColor];
		self.layer.borderColor = [[UIColor whiteColor] CGColor];
		self.layer.borderWidth = borderWidth;
		self.layer.cornerRadius = radius;
		
		if ([self.layer respondsToSelector:@selector(setShadowOffset:)])
			self.layer.shadowOffset = CGSizeMake(0.25, 0.25);
		
		if ([self.layer respondsToSelector:@selector(setShadowColor:)])
			self.layer.shadowColor = [[UIColor blackColor] CGColor];
		
		if ([self.layer respondsToSelector:@selector(setShadowRadius:)])
			self.layer.shadowRadius = borderWidth;
		
		if ([self.layer respondsToSelector:@selector(setShadowOpacity:)])
			self.layer.shadowOpacity = 0.75;
		
		[self setNeedsDisplay];
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
	CGContextRef ctx = UIGraphicsGetCurrentContext();
	CGContextSetShouldAntialias(ctx, true);
	
	CGFloat xsize = self.bounds.size.width / 6;
	CGFloat borderWidth = self.bounds.size.width / 10;

	CGContextSaveGState(ctx);
	
	CGContextSetLineCap(ctx, kCGLineCapRound);
	CGContextSetLineWidth(ctx, borderWidth);
	CGContextSetStrokeColorWithColor(ctx, [[UIColor whiteColor] CGColor]);
	
	CGFloat width = self.bounds.size.width;
	CGPoint start1 = CGPointMake(width / 2 - xsize, width / 2 - xsize);
	CGPoint end1 = CGPointMake(width / 2 + xsize, width / 2 + xsize);
	CGPoint start2 = CGPointMake(width / 2 + xsize, width / 2 - xsize);
	CGPoint end2 = CGPointMake(width / 2 - xsize, width / 2 + xsize);
	
	CGContextBeginPath(ctx);
	CGContextMoveToPoint(ctx, start1.x, start1.y);
	CGContextAddLineToPoint(ctx, end1.x, end1.y);
	CGContextStrokePath(ctx);
	
	CGContextBeginPath(ctx);
	CGContextMoveToPoint(ctx, start2.x, start2.y);
	CGContextAddLineToPoint(ctx, end2.x, end2.y);
	CGContextStrokePath(ctx);
	
	CGContextRestoreGState(ctx);
}

@end

gistfile3.m

CGFloat closeSize = 26.0;
CGRect butframe = CGRectMake(0.0, 0.0, closeSize, closeSize);
butframe.origin.x = contentView.frame.origin.x - closeSize / 2;
butframe.origin.y = contentView.frame.origin.y - closeSize / 2;

DNCloseButton *button = [[[DNCloseButton alloc] initWithFrame:butframe] autorelease];
[button addTarget:self action:@selector(closePopup:) forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:button];