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。