Have you ever wanted to use a UIAlertView but you hate the default blue color? Ever wonder why they don’t have a simple way to change the color of the alerts? I had these questions and the only answer I found was to subclass UIAlertView and override the drawRect method. This is my first attempt at using Quartz so if anyone knows a better way to draw it let me know via the contact form.

Updated for iOS 4.2 Thanks to Cyrillian Studios

[CustomAlert setBackgroundColor:[UIColor blueColor] 
	withStrokeColor:[UIColor greenColor]];
CustomAlert.h
#import <UIKit/UIKit.h>
 
@interface CustomAlert : UIAlertView
{
 
}
 
+ (void) setBackgroundColor:(UIColor *) background 
	withStrokeColor:(UIColor *) stroke;
 
@end
CustomAlert.m
#import "CustomAlert.h"
 
@interface CustomAlert (Private)
 
- (void) drawRoundedRect:(CGRect) rect inContext:(CGContextRef) 
	context withRadius:(CGFloat) radius;
 
@end
 
static UIColor *fillColor = nil;
static UIColor *borderColor = nil;
 
@implementation CustomAlert
 
+ (void) setBackgroundColor:(UIColor *) background 
	withStrokeColor:(UIColor *) stroke
{
	if(fillColor != nil)
	{
		[fillColor release];
		[borderColor release];
	}
 
	fillColor = [background retain];
	borderColor = [stroke retain];
}
 
- (id)initWithFrame:(CGRect)frame
{
    if((self = [super initWithFrame:frame]))
	{
        if(fillColor == nil)
		{
			fillColor = [[UIColor blackColor] retain];
			borderColor = [[UIColor colorWithHue:0.625 
				saturation:0.0 brightness:0.8 alpha:0.8] 
					retain];
		}
    }
 
    return self;
}
 
- (void)layoutSubviews
{
	for (UIView *sub in [self subviews])
	{
		if([sub class] == [UIImageView class] && sub.tag == 0)
		{
			// The alert background UIImageView tag is 0, 
			// if you are adding your own UIImageView's 
			// make sure your tags != 0 or this fix 
			// will remove your UIImageView's as well!
			[sub removeFromSuperview];
			break;
		}
	}
}
 
- (void)drawRect:(CGRect)rect
{	
	CGContextRef context = UIGraphicsGetCurrentContext();
 
	CGContextClearRect(context, rect);
	CGContextSetAllowsAntialiasing(context, true);
	CGContextSetLineWidth(context, 0.0);
	CGContextSetAlpha(context, 0.8); 
	CGContextSetLineWidth(context, 2.0);
	CGContextSetStrokeColorWithColor(context, [borderColor CGColor]);
	CGContextSetFillColorWithColor(context, [fillColor CGColor]);
 
	// Draw background
	CGFloat backOffset = 2;
	CGRect backRect = CGRectMake(rect.origin.x + backOffset, 
		rect.origin.y + backOffset, 
		rect.size.width - backOffset*2, 
		rect.size.height - backOffset*2);
 
	[self drawRoundedRect:backRect inContext:context withRadius:8];
	CGContextDrawPath(context, kCGPathFillStroke);
 
	// Clip Context
	CGRect clipRect = CGRectMake(backRect.origin.x + backOffset-1, 
		backRect.origin.y + backOffset-1, 
		backRect.size.width - (backOffset-1)*2, 
		backRect.size.height - (backOffset-1)*2);
 
	[self drawRoundedRect:clipRect inContext:context withRadius:8];
	CGContextClip (context);
 
	//Draw highlight
	CGGradientRef glossGradient;
	CGColorSpaceRef rgbColorspace;
	size_t num_locations = 2;
	CGFloat locations[2] = { 0.0, 1.0 };
	CGFloat components[8] = { 1.0, 1.0, 1.0, 0.35, 1.0, 1.0, 1.0, 0.06 };
	rgbColorspace = CGColorSpaceCreateDeviceRGB();
	glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, 
		components, locations, num_locations);
 
	CGRect ovalRect = CGRectMake(-130, -115, (rect.size.width*2), 
		rect.size.width/2);
 
	CGPoint start = CGPointMake(rect.origin.x, rect.origin.y);
	CGPoint end = CGPointMake(rect.origin.x, rect.size.height/5);
 
	CGContextSetAlpha(context, 1.0); 
	CGContextAddEllipseInRect(context, ovalRect);
	CGContextClip (context);
 
	CGContextDrawLinearGradient(context, glossGradient, start, end, 0);
 
	CGGradientRelease(glossGradient);
	CGColorSpaceRelease(rgbColorspace); 
}
 
- (void) drawRoundedRect:(CGRect) rrect inContext:(CGContextRef) context 
		withRadius:(CGFloat) radius
{
	CGContextBeginPath (context);
 
	CGFloat minx = CGRectGetMinX(rrect), midx = CGRectGetMidX(rrect), 
		maxx = CGRectGetMaxX(rrect);
 
	CGFloat miny = CGRectGetMinY(rrect), midy = CGRectGetMidY(rrect), 
		maxy = CGRectGetMaxY(rrect);
 
	CGContextMoveToPoint(context, minx, midy);
	CGContextAddArcToPoint(context, minx, miny, midx, miny, radius);
	CGContextAddArcToPoint(context, maxx, miny, maxx, midy, radius);
	CGContextAddArcToPoint(context, maxx, maxy, midx, maxy, radius);
	CGContextAddArcToPoint(context, minx, maxy, minx, midy, radius);
	CGContextClosePath(context);
}
 
- (void)dealloc
{
    [super dealloc];
}
 
@end