Navigation.pop()和Navigation.push()行为异常 [英] Navigation.pop() and Navigation.push() acting strangely
问题描述
我正在使用Flutter在我的应用程序中创建一个Sign-Up部分，我正在尝试执行以下操作:
I'm creating a Sign-Up section in my application using Flutter and I'm trying to do the following:
-
用户单击注册"
The user clicks Sign-Up
用户在注册过程中的任何阶段都按下后退按钮
The user presses the back button at any stage during sign-up
然后弹出一个警告对话框，询问用户是否真的要退出注册过程
Then an alert dialog pops up asking if the user really wants to leave sign-up process
用户按下是
然后将用户带回到应用程序的第一(主)页面.
The user is then taken back to the first (main) page of the app.
单击注册后此功能适用于第一页，但是当我进入第二页时，步骤4 使我停留在同一页上，然后再次尝试时可以使用.但这不是事实.
This works for the first page after I click sign-up, but when I get to the second page, step 4 keeps me on the same page, then when I try it again, it works. But this shouldn't be the case.
经过调试后，我发现了问题，但不知道为什么会发生.
After some debugging, I found the issue, but I don't know why it's happening.
我在onBackPressed()函数末尾的第二个代码段中以注释形式写了这个问题，以便清楚地知道它的中断位置:).
I wrote the issue as a comment in my second code snippet, at the end of the onBackPressed() function so it's clear as to where it's breaking :).
这是我的代码，用于从我的 main.dart 导航至注册过程页面:
Here is my code for navigating to the sign-up process page from my main.dart:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SignUp())
)
然后在注册过程中的每一页上，每当我进入下一页时，我都会执行Navigation.pop(context)来弹出从堆栈中弹出当前的注册页，然后执行
Then for each page during the sign-up process, whenever I go onto the next page I do a Navigation.pop(context) to pop the current sign-up page off the stack the do a Navigation.push() right after to push the next page on.
以下是每个注册页面中后退按钮功能的代码:
Here is the code for the back button functionality in each sign-up page:
bool backIsPressed = false;
Tools _tools = new Tools();
@override
void initState() {
super.initState();
BackButtonInterceptor.add(onBackPressed);
}
@override
void dispose() {
BackButtonInterceptor.remove(onBackPressed);
super.dispose();
}
bool onBackPressed(bool stopDefaultButtonEvent) {
this.backIsPressed = !backIsPressed;
if(backIsPressed) {
_tools.yesNoAlert(
context,
"Going Back?",
"Are you sure you want back? Changes made will not be saved.",
() {
this.backIsPressed = false;
Navigator.pop(context, true);
},
() {
this.backIsPressed = false;
Navigator.pop(context, false);
},
).then((res) {
// ---------------- BREAKS HERE -----------------
// "res" returns null the first time YES is pressed
// But Navigation.pop(context, true) should return true according to Flutter's docs
if(res) {
Navigator.pop(context);
}
});
}
else {
Navigator.pop(context);
}
return true;
}
最后，是Tools类中的yesOrNoAlert()函数.
Future<bool> yesNoAlert(BuildContext context, String title,
String description, Function yesFunction, Function noFunction) {
this._isDialogOpen = true;
return showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return AlertDialog(
title: new Text(title),
content: new Text(description),
actions: <Widget>[
new FlatButton(
child: new Text('Yes'),
onPressed: () {
_isDialogOpen = false;
yesFunction();
},
),
new FlatButton(
child: new Text('No'),
onPressed: () {
_isDialogOpen = false;
noFunction();
},
)
],
);
});
}
希望我解释得很好.
推荐答案
如果要返回第一页，而不是pop()，则当用户选择是"时可以使用popUntil()...不需要通过"res"
if you want go back to the first page, instead of pop(), you can use popUntil() when the user selects yes... no need to pass "res"
在此处了解更多信息: https://api.flutter.dev/flutter/widgets/Navigator/popUntil.html
Learn more about it here: https://api.flutter.dev/flutter/widgets/Navigator/popUntil.html
这篇关于Navigation.pop()和Navigation.push()行为异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
