UINavigationBar

//添加标题
    self.navigationItem.title = @"nav";

    //添加图片
    self.navigationItem.titleView =[UIButton buttonWithType:UIButtonTypeContactAdd];


    //在iOS7以后
    //默认会把导航条上的按钮渲染成蓝色
    //style不管怎么设置都没有任何效果
    //不管image是什么颜色，都会被渲染成蓝色

    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"back" style:UIBarButtonItemStyleDone target:self action:@selector(back)];


    //在iOS7以后避免图片被渲染为蓝色
    UIImage *image = [UIImage imageNamed:@"menu"];
    image = [image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithImage:image style:UIBarButtonItemStyleDone target:self action:@selector(push)];


    //如果要给navigationBar上按钮设置俩张图片，需要定义button
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setImage:[UIImage imageNamed:@"cell_OK"] forState:UIControlStateNormal];

    [button setImage:[UIImage imageNamed:@"cell_NO"] forState:UIControlStateHighlighted];

    //控制的尺寸由图片决定，仅仅是设置尺寸，不能设置位置
    [button sizeToFit];
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:button];