我在flutter 3.0和dart sdk 2.17.0上运行我的flutter应用程序。
但是现在我在这里发现了一个警告，像这样-
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_navigation/src/router_report.dart:53:22: Warning: Operand of null-aware
operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/widgets/bindi
ng.dart').
WidgetsBinding.instance!.addPostFrameCallback((_) {
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_navigation/src/snackbar/snackbar.dart:452:22: Warning: Operand of
null-aware operation '!' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance!.addPostFrameCallback(
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_navigation/src/extension_navigation.dart:357:24: Warning: Operand of
null-aware operation '!' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance!.addPostFrameCallback((_) {
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_navigation/src/extension_navigation.dart:468:24: Warning: Operand of
null-aware operation '!' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance!.addPostFrameCallback((_) {
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_state_manager/src/simple/get_controllers.dart:90:20: Warning: Operand
of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/widgets/bindi
ng.dart').
WidgetsBinding.instance!.addObserver(this);
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_state_manager/src/simple/get_controllers.dart:96:20: Warning: Operand
of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/widgets/bindi
ng.dart').
WidgetsBinding.instance!.removeObserver(this);
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_state_manager/src/rx_flutter/rx_notifier.dart:130:22: Warning: Operand
of null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance?.addPostFrameCallback((_) => onReady());
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/get-4.
6.1/lib/get_state_manager/src/rx_flutter/rx_disposable.dart:20:22: Warning: Operand
of null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance?.addPostFrameCallback((_) => onReady());
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/flutte
r_easyloading-3.0.3/lib/src/widgets/overlay_entry.dart:35:26: Warning: Operand of
null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
if (SchedulerBinding.instance?.schedulerPhase ==
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/flutte
r_easyloading-3.0.3/lib/src/widgets/overlay_entry.dart:37:24: Warning: Operand of
null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance?.addPostFrameCallback((_) {
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/flutte
r_easyloading-3.0.3/lib/src/widgets/container.dart:64:24: Warning: Operand of
null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance?.schedulerPhase ==
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/flutte
r_easyloading-3.0.3/lib/src/widgets/container.dart:101:24: Warning: Operand of
null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance?.addPostFrameCallback((_) => completer
^
/usr/local/Caskroom/flutter/2.0.2/flutter/.pub-cache/hosted/pub.dartlang.org/flutte
r_easyloading-3.0.3/lib/src/widgets/container.dart:112:24: Warning: Operand of
null-aware operation '?.' has type 'SchedulerBinding' which excludes null.
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart'
('/usr/local/Caskroom/flutter/2.0.2/flutter/packages/flutter/lib/src/scheduler/bin
ding.dart').
SchedulerBinding.instance?.addPostFrameCallback((_) => completer
^
Syncing files to device iPhone SE (3rd generation)... 805ms
有什么问题?在以前版本的flutter中没有显示。
In Flutter 3.0
SchedulerBinding.instance!.addPostFrameCallback(...);
SchedulerBinding.instance.addPostFrameCallback(...);
似乎绑定包里面有一些Schedulerbindings代码，需要更新。
你可以在本地复制包并修改包中的代码。
或者更改依赖关系....或者等到该包更新并恢复到Flutter 2.10.5
您可以在这里阅读有关Flutter 3.0的更改
我使用一个工具来更改版本Flutter Sidekick，您可以为不同的项目选择不同的Flutter版本。