[self.navigationItem setHidesBackButton:YES];
    //用来放searchBar的View
    UIView *titleView = [[UIView alloc] initWithFrame:CGRectMake(5, 7, self.view.frame.size.width, 30)];
    //创建searchBar
    UISearchBar *searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(titleView.frame) - 15, 30)];
    //默认提示文字
    searchBar.placeholder = @"搜索内容";
 
    //代理
    searchBar.delegate = self;
    //显示右侧取消按钮
    searchBar.showsCancelButton = YES;
    //拿到取消按钮
    UIButton *cancleBtn = [searchBar valueForKey:@"cancelButton"];
    //设置按钮上的文字
    [cancleBtn setTitle:@"发布" forState:UIControlStateNormal];
    //设置按钮上文字的颜色
    [cancleBtn setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [titleView addSubview:searchBar];
    self.searchBar = searchBar;
    self.navigationItem.titleView = titleView;