Swift 对 begin/end 外观转换的不平衡调用

Question

这已经困扰我一段时间了。我在 UITabBarController 中有一个 UISplitViewController。主视图是一个 TableView。当我点击一个单元格时，我会调出一个非常基本的视图控制器，其中只有一个 UIButton 居中。这是视图控制器的代码：

class TestViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    @IBOutlet weak var button: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func buttonPressed(sender: AnyObject) {
        let pickerC = UIImagePickerController()
        pickerC.delegate = self

        pickerC.modalPresentationStyle = .Popover
        pickerC.popoverPresentationController?.sourceView = button as UIView
        pickerC.popoverPresentationController?.sourceRect = (button as UIView).bounds
        pickerC.popoverPresentationController?.permittedArrowDirections = UIPopoverArrowDirection.Any
        self.presentViewController(pickerC, animated: true, completion: nil)//4
    }

    func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
        self.dismissViewControllerAnimated(true, completion: nil)
    }

    func imagePickerControllerDidCancel(picker: UIImagePickerController) {
       self.dismissViewControllerAnimated(true, completion: nil)
    }
}

如果我单击取消或 select 和图像，选择器控制器会正确关闭。当我单击后退按钮 return 到 TableView 时，问题就来了，我收到：

Unbalanced calls to begin/end appearance transitions for <TestViewController: 0x7fb882a72380>.

TestViewController 非常基础，为什么会这样？

Answer 1

如果您在先前的事务（动画）正在进行时尝试推送新的视图控制器，则会出现此问题。因此，请检查您的代码流并进行适当的更改。检查您的解雇和呈现视图动画。您可以使用属性 setAnimation 来 'YES/NO' 解决这个

设置animated:NO，或许可以解决您的问题

Answer 2

对我来说，这个奇怪的问题是由于实施 UISplitViewController 后的以下行而发生的

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
.
.
.
    // splitViewController.preferredDisplayMode = .PrimaryOverlay
.
.
.
    }

通过在 didFinishLaunchingWithOptions 中评论这一行问题得到解决。

Answer 3

就我而言，我忘记删除故事板文件。我把它删除后，这个警告就没有了。

Swift 对 begin/end 外观转换的不平衡调用

Swift Unbalanced calls to begin/end appearance transitions for

uiviewcontroller

uiimagepickercontroller

ios

swift