IOS:UINavigationBar、navigationItem

    UINavigationBar* navigation = [[UINavigationBaralloc] initWithFrame:CGRectMake(100,150, 568, 50)];

    [self.viewaddSubview:navigation];

    

    UINavigationItem* navigationItem = [[UINavigationItemalloc] init];

    [navigationpushNavigationItem:navigationItem animated:YES];

    

    UIButton *backButton = [UIButtonbuttonWithType:UIButtonTypeCustom];

    backButton.frame =CGRectMake(0.0,0.0, 55.0, 30.0);

    [backButton setTitle:@"返回"forState:UIControlStateNormal];

    backButton.titleLabel.font = [UIFontsystemFontOfSize:14.0];

    [backButton addTarget:selfaction:@selector(backAction)forControlEvents:UIControlEventTouchUpInside];

   UIBarButtonItem *temporaryBarButtonItem = [[UIBarButtonItemalloc] initWithCustomView:backButton];

    temporaryBarButtonItem.style =UIBarButtonItemStylePlain;

    

    navigationItem.leftBarButtonItem = temporaryBarButtonItem;