Question

I have an application where I am showing an alert message using UIAlertView. By default the color of the dialog box is blue. Can anyone tell me, how to change the color of that? Can it be changed?

Answer 1

Use Like This

   [CustomAlert setBackgroundColor:[UIColor blueColor] 
    withStrokeColor:[UIColor greenColor]];

.h and .m File’s Content

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