iphone - 如何在iOS中更改UIAlertView对话框的颜色？

Question

我有一个应用程序，使用UIAlertView在其中显示警报消息。默认情况下，对话框的颜色为蓝色。谁能告诉我，如何改变颜色？可以更改吗？

Answer 1

像这样使用

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

.h和.m文件的内容

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