Ios 请求的属性表达式的地址

我正在通过引用将UINavigationController传递给另一个类。但它显示请求的属性表达式的地址出现错误

MyUtil*util=[[MyUtil alloc]init]

[util navandbacktn:&self.navigationController]；//这里有错误

MyUtil.m

-(void)NavAndBackBtn:(UINavigationController **)nav // ** for passing by reference
{

 UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];

[btn setImage:[UIImage imageNamed:@"icon_back.png"] forState:UIControlStateNormal];

[button setFrame:CGRectMake(0,0,36,20);

UIBarButtonItem *barbtn = [[UIBarButton alloc] initWithCustomView:btn];

//*nav.navigationController.navigationItem.leftBarButtonItem = barbtn;// this gives error
//then i set this nav to Util nav

self.main_nav_ofUtilClass = *nav;

sefl.main_nav_ofUtilClass.navigationItem.leftBarButtonItem =barbtn;
}

问题

-(void)NavAndBackBtn:(UINavigationController **)nav // ** for passing by reference
{

 UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];

[btn setImage:[UIImage imageNamed:@"icon_back.png"] forState:UIControlStateNormal];

[button setFrame:CGRectMake(0,0,36,20);

UIBarButtonItem *barbtn = [[UIBarButton alloc] initWithCustomView:btn];

//*nav.navigationController.navigationItem.leftBarButtonItem = barbtn;// this gives error
//then i set this nav to Util nav

self.main_nav_ofUtilClass = *nav;

sefl.main_nav_ofUtilClass.navigationItem.leftBarButtonItem =barbtn;
}

如何通过引用传递UINavigationController。 所以我在另一个类中对UINavigationController所做的任何更改都会发生在它身上

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我只是想用另一个类名MyUtil向UINavigationController添加一个back按钮图像，我认为您在方法名上犯了错误

-(void)NavAndBackBtn:(UINavigationController **)nav

用这个代替

-(void)NavAndBackBtn:(UINavigationController *)nav

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删除

**

如果要添加按钮，为什么不尝试使用类别？保留一个布尔值以在默认值和自定义值之间切换。它不起作用。但我已通过参数将其更改为UINavigationItem它正在工作事件未处理请参阅。。。