Ios 无法在布局视图xcode情节提要集上创建按钮

我曾尝试在屏幕上创建带有自定义图像中心的按钮，但无效。因此，我求助于以编程方式为主self.view创建按钮。在执行时，不能添加按钮

下面是我的代码。请查看

 UIButton *buttonA = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 88, 30)];
    [buttonA setImage:[UIImage imageNamed:@"rc_logo.png"] forState:UIControlStateNormal];
    UIBarButtonItem *buttonItemB = [[UIBarButtonItem alloc] initWithCustomView:buttonA];
    navigationItem.rightBarButtonItem = buttonItemB;
    [navigationBar pushNavigationItem:navigationItem animated:NO];


    UIImage * ssssImage = [UIImage imageNamed:@"menu_back.png"] ;
    UIButton * btnPair ;
    [self setPosition : btnPair  image: ssssImage  positionAt: CGRectMake(self.view.frame.size.width/2 -  ssssImage.size.width/2,
                                                                          self.view.frame.size.height * 0.18 ,
                                                                          ssssImage.size.width/2,  ssssImage.size.height/2)];

    [self.scrollContain addSubview:btnPair];
}


-(void) setPosition  : (UIButton * ) btn image :  (UIImage * ) deviceImage  positionAt : (CGRect) frame   {


    btn = [[UIButton alloc] initWithFrame: frame];
    [btn setImage:deviceImage forState:UIControlStateNormal ];
    [btn setFrame: frame];

    btn.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;
    btn.titleLabel.textAlignment = NSTextAlignmentLeft;


}

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试着给它背景色的调试过程和检查，通过放置断点和观察帧和隐藏属性的按钮，你们正在创建

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请指定哪个按钮不添加UIBarButton或UIButton？

UIButtons，而不是UIBarBUttons