改UIsearchbar 的背景和cancel按钮

1 修改背景
   searchbar =[[UISearchBar alloc]initWithFrame:CGRectMake(0,KTopBarHeight, 320, KTopBarHeight)];
    searchbar.delegate=self;
    searchbar.keyboardType = UIKeyboardTypeDefault;
    //[[searchbar.subviews objectAtIndex:0]removeFromSuperview];
    UIImage *img = [[UIImage imageNamed: @"searchBar_bg.png"]stretchableImageWithLeftCapWidth:0 topCapHeight:22];      
    UIImageView *v = [[[UIImageView alloc] initWithFrame:CGRectZero] autorelease];      
    [v setImage:img];  
    v.bounds = CGRectMake(0, 0, searchbar.frame.size.width, searchbar.frame.size.height); 
    
    NSArray *subs = searchbar.subviews;      
    for (int i = 0; i < [subs count]; i++) {          
        id subv = [searchbar.subviews objectAtIndex:i];
                if ([subv isKindOfClass:NSClassFromString(@"UISearchBarBackground")])  
        {              
            CGRect viewRect = [subv frame];              
            [v setFrame:viewRect];              
            [searchbar insertSubview:v atIndex:i];          
        }      
    }  
     
   
    searchbar.placeholder=@"请输入疾病名,症状或问题";
2 修改cancel按钮

  -(void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar{
    searchBar.showsCancelButton=YES;
    btn.hidden=NO;
    searchBar.showsCancelButton = YES;
    for(id cc in [searchBar subviews])
    {
        if([cc isKindOfClass:[UIButton class]])
        {
            UIButton *sbtn = (UIButton *)cc;
            [sbtn setTitle:@"取消"  forState:UIControlStateNormal];
            [sbtn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
        }
    }
}