UIBarButtonItem-添加自定義Left或者Right按鈕

1.添加返回導航按鈕backBarButtonItem
1.用系統自帶的返回按鈕
 UIBarButtonItem *leftBarButtonItem = [[UIBarButtonItem alloc]
                                          initWithTitle:@"返回"
                                          style:UIBarButtonSystemItemCancel
                                          target:self
                                          action:@selector(doClickBackAction:)];
    self.navigationItem.backBarButtonItem = leftBarButtonItem;
 
2.本身定義返回按鈕
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];
    backButton.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;
    [leftBarButtonItem release];
    [backButton release];