iOS6下修改UISearchBar的输入框背景去除阴影，并设置成iOS7风格

修改UISearchBar的输入框背景去除阴影，并设置成iOS7风格

UITextField *searchField;
NSUInteger numViews = [searchBar.subviews count];
for(int i = 0; i < numViews; i++) {
    if([[searchBar.subviews objectAtIndex:i] isKindOfClass:[UITextField class]]) { 
        searchField = [searchBar.subviews objectAtIndex:i];
    }
}
if(!(searchField == nil)) {
    searchField.textColor = [UIColor blackColor];
    [searchField setBackground: [UIImage imageNamed:@"white.png"]];
    [searchField setBorderStyle:UITextBorderStyleNone];

    searchField.layer.cornerRadius = 6;  

    searchField.font = [UIFont boldSystemFontOfSize:14];
}