iOS 11 UINavigationItem 去除左右间隙的方法

//0:leftBarButtonItems,1:rightBarButtonItems
- (void)initBarItem:(UIView*)view withType:(int)type{
  UIBarButtonItem * buttonItem = [[UIBarButtonItem alloc]initWithCustomView:view];
  //解决按钮不靠左 靠右的问题.iOS 11系统需要单独处理
  UIBarButtonItem * spaceItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
  spaceItem.width = -16;//这个值可以根据自己需要自己调整
  switch (type) {
    case 0:
      if (!IS_IOS_VERSION_11) {
        self.navigationItem.leftBarButtonItems =@[spaceItem,buttonItem];
      }else{
        self.navigationItem.leftBarButtonItems =@[buttonItem];
      }
      break;
    case 1:
      if (!IS_IOS_VERSION_11) {
        self.navigationItem.rightBarButtonItems =@[spaceItem,buttonItem];
      }else{
        self.navigationItem.rightBarButtonItems =@[buttonItem];
      }
      break;
      
    default:
      break;
  }
}

-(void)viewDidLayoutSubviews{
  if (!IS_IOS_VERSION_11) return;
  UINavigationItem * item=self.navigationItem;
  NSArray * array=item.leftBarButtonItems;
  if (array&&array.count!=0){
    //这里需要注意,你设置的第一个leftBarButtonItem的customeView不能是空的,也就是不要设置UIBarButtonSystemItemFixedSpace这种风格的item
    UIBarButtonItem * buttonItem=array[0];
    UIView * view =[[[buttonItem.customView superview] superview] superview];
    NSArray * arrayConstraint=view.constraints;
    for (NSLayoutConstraint * constant in arrayConstraint) {
      if (fabs(constant.constant)==16) {
        constant.constant=0;
      }
    }
  }
}