如何在iOS中更改UIAlertView对话框的颜色? [英] How to change color of the UIAlertView dialog in iOS?

问题描述

我有一个应用程序，其中正在使用UIAlertView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?

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?

推荐答案

像这样使用

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

.h和.m文件的内容

.h and .m File's Content

CustomAlert.h

CustomAlert.h

#import <UIKit/UIKit.h>

@interface CustomAlert : UIAlertView
{

}

+ (void) setBackgroundColor:(UIColor *) background 
    withStrokeColor:(UIColor *) stroke;

@end

CustomAlert.m

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

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