【发布时间】：2021-12-31 21:04:53
【问题描述】：
我想使用 maps_launcher 包启动 Google 地图。
当我将下面的 TextButton 代码复制到 MaterialApp 主页部分的新项目中（或剥离我自己的 main.dart）时，它可以正常工作。 （编辑：它必须包装在容器或脚手架中才能工作，否则我会收到相同的类型不匹配错误。）
但是，由于某种我不知道的原因，我在所需的结构中不断遇到两个错误之一：
场景/错误 A
当我使用这段代码时：
onPressed: MapsLauncher.launchQuery(businesses[index].address)
我收到此错误：
The argument type 'Future<bool>' can't be assigned to the parameter type 'void Function()?'.
场景/错误 B
当我使用这段代码时：
我收到此错误：
════════ Exception caught by widgets library ═══════════════════════════════════
The following _TypeError was thrown building:
type 'String' is not a subtype of type 'Widget'
When the exception was thrown, this was the stack
#0 BusinessList.build.<anonymous closure>.<anonymous closure>
#1 SliverChildBuilderDelegate.build
#2 SliverMultiBoxAdaptorElement._build
#3 SliverMultiBoxAdaptorElement.createChild.<anonymous closure>
#4 BuildOwner.buildScope
#5 SliverMultiBoxAdaptorElement.createChild
#6 RenderSliverMultiBoxAdaptor._createOrObtainChild.<anonymous closure>
#7 RenderObject.invokeLayoutCallback.<anonymous closure>
#8 PipelineOwner._enableMutationsToDirtySubtrees
#9 RenderObject.invokeLayoutCallback
#10 RenderSliverMultiBoxAdaptor._createOrObtainChild
#11 RenderSliverMultiBoxAdaptor.addInitialChild
#12 RenderSliverList.performLayout
#13 RenderObject.layout
#14 RenderSliverEdgeInsetsPadding.performLayout
#15 RenderSliverPadding.performLayout
#16 RenderObject.layout
#17 RenderViewportBase.layoutChildSequence
#18 RenderViewport._attemptLayout
#19 RenderViewport.performLayout
#20 RenderObject.layout
#21 RenderProxyBoxMixin.performLayout
#22 RenderObject.layout
#23 RenderProxyBoxMixin.performLayout
#24 RenderObject.layout
#25 RenderProxyBoxMixin.performLayout
#26 RenderObject.layout
#27 RenderProxyBoxMixin.performLayout
#28 RenderObject.layout
#29 RenderProxyBoxMixin.performLayout
#30 RenderObject.layout
#31 RenderProxyBoxMixin.performLayout
#32 RenderObject.layout
#33 RenderProxyBoxMixin.performLayout
#34 RenderObject.layout
#35 RenderProxyBoxMixin.performLayout
#36 RenderCustomPaint.performLayout
#37 RenderObject.layout
#38 RenderProxyBoxMixin.performLayout
#39 RenderObject.layout
#40 MultiChildLayoutDelegate.layoutChild
#41 _ScaffoldLayout.performLayout
#42 MultiChildLayoutDelegate._callPerformLayout
#43 RenderCustomMultiChildLayoutBox.performLayout
#44 RenderObject._layoutWithoutResize
#45 PipelineOwner.flushLayout
#46 RendererBinding.drawFrame
#47 WidgetsBinding.drawFrame
#48 RendererBinding._handlePersistentFrameCallback
#49 SchedulerBinding._invokeFrameCallback
#50 SchedulerBinding.handleDrawFrame
#51 SchedulerBinding._handleDrawFrame
#55 _invoke (dart:ui/hooks.dart:150:10)
#56 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:270:5)
#57 _drawFrame (dart:ui/hooks.dart:114:31)
(elided 3 frames from dart:async)
完整代码
这是产生上述错误的代码（在粘贴过程中删除了包导入）：
class BusinessList extends StatelessWidget {
const BusinessList({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Business List')),
body: StreamBuilder(
stream: FirebaseFirestore.instance
.collection('businesses')
.snapshots()
.map((snapshot) => snapshot.docs
.map((doc) => Business.fromJson(doc.data()))
.toList()),
builder: (BuildContext context, AsyncSnapshot<List> snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return const CircularProgressIndicator();
}
if (snapshot.hasData) {
if (snapshot.data!.isNotEmpty) {
final businesses = snapshot.data;
return ListView.builder(
itemCount: businesses!.length,
itemBuilder: (BuildContext context, int index) {
return Card(
child: Column(
children: [
ExpansionTile(
leading: const Icon(Icons.business),
title: Text(businesses[index].name),
subtitle: Text(businesses[index].category),
children: [
ListTile(
leading: const Icon(Icons.location_pin),
title: TextButton(
child: businesses[index].address,
onPressed: () => MapsLauncher.launchQuery(
businesses[index].address),
),
),
],
),
],
),
);
},
);
}
}
return const Text('error');
},
),
);
}
}
我的代码（第 42 行）的红色下划线部分是：
MapsLauncher.launchQuery(businesses[index].address)
【问题讨论】：
-
由于未来的方法，请尝试使用
onPressed()async{ await MapsLauncher...}。如果需要，请等待 -
@YeasinSheikh 感谢您分享这个想法！可悲的是，无论是否使用 async/await，它都会返回相同的错误（场景 B）。 （试过：onPressed: () async =>await MapsLauncher...）
标签： flutter flutter-onpressed url-launcher