修复很简单:
在自己定义的item前边加一个FixedSpace的BarButton.
UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
negativeSpacer.width = -15;
self.navigationItem.leftBarButtonItems = @[negativeSpacer, [[UIBarButtonItem alloc] initWithCustomView:button]];
