UINavigationController添加 UINavigationItem，我们可以这样写：

1.添加返回导航按钮backBarButtonItem

1.用系统自带的返回按钮

UIBarButtonItem *leftBarButtonItem = [[UIBarButtonItem alloc]
initWithTitle:@"返回"
style:UIBarButtonSystemItemCancel
target:self
action:@selector(doClickBackAction:)];
    self.navigationItem.backBarButtonItem = leftBarButtonItem;

2.自己定义返回按钮

UIImage* backImage = [UIImage imageNamed:@"btn_back.png"];
 
CGRect backframe = CGRectMake(0,0,54,30);
 
UIButton* backButton= [[UIButton alloc] initWithFrame:backframe];
 
    [backButton setBackgroundImage:backImage forState:UIControlStateNormal];
 
    [backButton setTitle:@"直播" forState:UIControlStateNormal];
titleLabel.font=[UIFont systemFontOfSize:13];
    [backButton addTarget:self action:@selector(doClickBackAction:) forControlEvents:UIControlEventTouchUpInside];
    
UIBarButtonItem* leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
UIBarButtonItem* leftBarButtonItem = [[UIBarButtonItem alloc] init];
    self.navigationItem.leftBarButtonItem = leftBarButtonItem;
release];
release];