从网上收集了一些自定义AlertView背景的方法，汇总一下以便有需要时使用。
UIAlertView *theAlert = [[[UIAlertView alloc] initWithTitle:@"Atention" message:@"我是中国人！" delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil] autorelease];
[theAlert show];
// undocument API UIAlertView类头文件里面带 “ _”的成员是可以通过 valueforkey来引用的。但这些都是不公开的，私有方法
UILabel *theTitle = [theAlert valueForKey:@"_titleLabel"];
[theTitle setTextColor:[UIColor greenColor]];
UILabel *theBody = [theAlert valueForKey:@"_bodyTextLabel"];
[theBody setTextColor:[UIColor blueColor]];
/* 第一种自定义方法
//
UIImageView *imgv = [theAlert valueForKey:@"_backgroundImageView"];
imgv.image = [UIImage imageNamed:@"loveChina.png"];
*/
//
/* 第二种自定义方法,因有过期属性的使用，所以新版iOS中无效
//
// undocument API
UIImage *theImage = [UIImage imageNamed:@"loveChina.png"];
theImage = [theImage stretchableImageWithLeftCapWidth:0.0 topCapHeight:0.0];
CGSize theSize = [theAlert frame].size;
UIGraphicsBeginImageContext(theSize);
[theImage drawInRect:CGRectMake(0, 0, theSize.width, theSize.height)];
theImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
theAlert.layer.contents = (id)[theImage CGImage]; // iOS4.0开始不支持contents属性
*/
//
/* 第三种自定义方法
//遍历theAlert对象的子view，获取其UIImageView视图
for (UIView *v in [theAlert subviews]) {
if ([v isKindOfClass:[UIImageView class]]) {
UIImage *theImage = [UIImage imageNamed:@"loveChina.png"];
((UIImageView *)v).image = theImage;
}
}
*/
/* 第四种自定义方法 */
UIView *additionBackgroundView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, theAlert.frame.size.width-30, theAlert.frame.size.height-20)];
additionBackgroundView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"loveChina.png"]];
#if TARGET_IPHONE_SIMULATOR
[theAlert insertSubview:additionBackgroundView atIndex:1];
#else
[theAlert insertSubview:additionBackgroundView atIndex:0];
#endif
[additionBackgroundView release];
第五种自定义代码：
1 UIAlertView *theAlert = [[[UIAlertView alloc] initWithTitle:@"Atention" message:@"我是中国人！" delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil] autorelease];
2 UIImage *alertImage = [UIImage imageNamed:@"loveChina.png"];
3 UIImageView *backgroundImageView = [[UIImageView alloc] initWithImage:alertImage];
4 backgroundImageView.frame = CGRectMake(0, 0, 282, 160);
5 backgroundImageView.contentMode = UIViewContentModeScaleToFill;
6 [theAlert addSubview:backgroundImageView];
7 [theAlert sendSubviewToBack:backgroundImageView];
8
9 [theAlert show];
10 [theAlert release];
运行效果如图：
第六种方式：使用一个定义扩展类JKCustomAlert (网上有下载）。
调用代码：
UIImage *backgroundImage = [UIImage imageNamed:@"Splatter.png"];
alert = [[JKCustomAlert alloc] initWithImage:backgroundImage text:NSLocalizedString(@"game over", nil)];
[alert show];
运行效果图：
为了在iOS4.2以上也有效，需增加些代码来手动隐藏原AlertView的背景视图:修改layoutSubviews方法
1 - (void) layoutSubviews {
2 for (UIView *v in [self subviews]) {
3 if ([v class] == [UIImageView class]) {
4 [v setHidden:YES];
5 }
6 }
7
8 //原来的代码继续
9 }