我想将UISearchBar控件自定义为如下图所示的样式:

首先我应该删除背景视图,然后找出UISearchBar中的UITextfiled,扩展UITextfiled的框架并删除它的边界.
这是我的代码:
UITextField *searchField;
NSUInteger numViews = [self.subviews count];
for(int i = 0; i != numViews; i++) {
if([[self.subviews objectAtIndex:i] isKindOfClass:[UITextField class]]) { //conform?
searchField = [self.subviews objectAtIndex:i];
}
}
if(!(searchField == nil)) {
[searchField setBorderStyle:UITextBorderStyleNone];
searchField.frame = self.frame; //modify the frame
}
[[self.subviews objectAtIndex:0]removeFromSuperview]; //remove the background.
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结果是UITextField的边界仍然存在.:(

我的问题是:1.为什么我不能修改UISearchBar的UITextField的外观?
2.如何在UISearchBar中删除UITextfield的边界.
非常感谢!