从AlertView例解设置view背景的几种方法

UIAlertView *alv_obj = [[[UIAlertView alloc] initWithTitle:@"AlertView"                                               message:@"This is Example！"                                               delegate:nil                                               cancelButtonTitle:@"cancel"                                               otherButtonTitles:@"confirm", nil] autorelease];
    [alv_obj 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    通过字典的方式取出其对象就可以操作其属性。如下：
    UILabel *theTitle = [alv_obj valueForKey:@"_titleLabel"];
    [theTitle setTextColor:[UIColor greenColor]];
    
    UILabel *theBody = [alv_obj valueForKey:@"_bodyTextLabel"];
    [theBody setTextColor:[UIColor blueColor]];
    
    /* 第一种自定义方法*/
     UIImageView *imgv = [alv_obj 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 = [alv_obj frame].size;
    
    UIGraphicsBeginImageContext(theSize);
    [theImage drawInRect:CGRectMake(0, 0, theSize.width, theSize.height)];
    theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    alv_obj.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alv_obj对象的子view，获取其UIImageView视图
   for (UIView *v in [alv_obj 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, alv_obj.frame.size.width-30, alv_obj.frame.size.height-20)];  additionBackgroundView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"loveChina.png"]];  #if TARGET_IPHONE_SIMULATOR  [alv_obj insertSubview:additionBackgroundView atIndex:1];  #else  [alv_obj insertSubview:additionBackgroundView atIndex:0];  #endif  [additionBackgroundView release];
  /*第五种自定义代码*/
  UIAlertView *theAlert = [[[UIAlertView alloc] initWithTitle:@"Atention"                                                 message:@"我是中国人！"                                                 delegate:nil                                                 cancelButtonTitle:@"取消"                                                 otherButtonTitles:@"确定", nil] autorelease];
  UIImage *alertImage = [UIImage imageNamed:@"loveChina.png"];
  UIImageView *backgroundImageView = [[UIImageView alloc] initWithImage:alertImage];
  backgroundImageView.frame = CGRectMake(0, 0, 282, 160);
  backgroundImageView.contentMode = UIViewContentModeScaleToFill;
  [theAlert addSubview:backgroundImageView];
  [theAlert sendSubviewToBack:backgroundImageView];
  
  [theAlert show];
  [theAlert release];

 

本质：作为复合控件，UIAlertView是由多个基本控件组合而成，每个基本控件的功能也是UIAlertView的功能的有效组成部分。所以，我们想修改UIAlertView的某个属性，可以通过修改控制UIAlertView的该属性的基本控件而达到目的。这是一个整体和局部的分析方法。例如本例，我们想修改UIAlertView的背景图，就是通过获取到控制UIAlertView的背景图的子控件UIImageView而达到目的的。

说点别的内容  uialertview 消失的调用方法

UIAlertView的消失本质其实是触发了一个dismiss事件。
触发这个事件有以下两种方法：
1.按钮点击，UIAlertView上如果有按钮，点击任何按钮都会触发该事件，UIAlertView消失；
2.代码模拟点击
[java] view plaincopyprint?
[AlertObject dismissWithClickedButtonIndex:0 animated:NO]