the navigation stack will not be updated

熊烨
2023-12-01

新手,用swift写ios应用时,报了个错误

popToViewController:transition: called on <UINavigationController 0x7f901981a400> while an existing transition or presentation is occurring; the navigation stack will not be updated.

场景是,在一个页面中点击按钮,弹出一个提示框UIAlertController

let dialog = UIAlertController(title: "提示", message: "请选择TODO的类型", preferredStyle: UIAlertControllerStyle.alert);
let okAction = UIAlertAction(title: "好的", style: .default, handler:{(action) ->Void in      
        print("onOK");
    });
let cancelAction = UIAlertAction(title: "取消", style: .cancel){(action) -> Void in
    print("onCancel")
};
dialog.addAction(cancelAction);
dialog.addAction(okAction);
self.present(dialog, animated: true, completion: {
    print("completion");
});

调用了ViewController的present方法进行弹窗,但是当点击按钮之后,窗口弹出后又自动消失了。

后来,发现是因为,按钮绑定了个close事件,close事件会触发关闭当前页。由于,UIAlertController是显示在当前ViewController之上的,如果关闭了的话,相当于它没有了载体。

记录。

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