在navigationBar中隐藏和显示后退按钮

Question

我有这两种方法：

func showSpinner()
{
    let spinner = UIActivityIndicatorView(activityIndicatorStyle: .White)
    spinner.startAnimating()

    self.navigationItem.leftBarButtonItem = UIBarButtonItem(customView: spinner)
    self.navigationItem.hidesBackButton = true
}

func hideSpinner()
{
    self.navigationItem.leftBarButtonItem = nil
    self.navigationItem.hidesBackButton = false
}

在viewDidLoad我致电showSpinner，然后在加载数据后，我致电hideSpinner。但backButton经常跳hideSpinner。如何解决？

Answer 1

删除微调器后，可以使用延迟显示后退按钮。像0.2秒或根据要求

func hideSpinner()
{
    self.navigationItem.leftBarButtonItem = nil
    dispatch_after(1, dispatch_get_main_queue()) { () -> Void in
        self.navigationItem.hidesBackButton = false
    };
}