SearchBar 设置

基本设置

    self.searchBar.barTintColor = [UIColor whiteColor];
    self.searchBar.layer.cornerRadius = 5;
    self.searchBar.layer.masksToBounds = YES;
    self.searchBar.barStyle = UISearchBarStyleMinimal;

背景色设置为白色后，上下各有一条灰色线条
可以如下处理：

   UIImageView *barImageView = [[[self.searchBar.subviews firstObject] subviews] firstObject];
    barImageView.layer.borderColor = [UIColor colorWithRed:245.0/255.0 green:245.0/255.0 blue:245.0/255.0 alpha:1.0].CGColor;
    barImageView.layer.borderWidth=1;