我有一个类似下面的主从关系:
public partial class LeaguesMDPage : MasterDetailPage
{
public LeaguesMDPage()
{
InitializeComponent();
Master = new LeaguesPage();
Detail = new NavigationPage(new DivisionsPage(new League()));
}
}
联赛页面(大师版)的设计具有以下列表视图:
<ListView
ItemsSource="{Binding Leagues}"
SelectedItem="{Binding SelectedLeague, Mode=TwoWay}"
IsPullToRefreshEnabled="True"
RefreshCommand="{Binding UpdateLeagues}"
IsRefreshing="{Binding IsBusy}"
>
并且背后的代码是
public partial class LeaguesPage : ContentPage
{
LeaguesViewModel vm;
public LeaguesPage()
{
InitializeComponent();
BindingContext = vm = new LeaguesViewModel(this);
}
protected override void OnAppearing()
{
base.OnAppearing();
vm.UpdateLeagues.Execute(false);
}
}
在LeaguesViewModel中,我通过设置SelectedLeague属性更新Detail页面并隐藏Master页面,代码如下:League _SelectedLeague;
public League SelectedLeague
{
get { return _SelectedLeague; }
set
{
_SelectedLeague = value;
OnPropertyChanged();
if (_SelectedLeague != null)
{
Debug.WriteLine($"Navigating to DivisionsPage with LeagueID {_SelectedLeague.ID}");
var mdp = (MasterDetailPage)App.Current.MainPage;
Device.OnPlatform(
Android: () => { mdp.IsPresented = false; },
iOS: () => { mdp.IsPresented = false; },
WinPhone: () => { },
Default: () => { mdp.IsPresented = false; }
);
mdp.Detail = new NavigationPage(new DivisionsPage(_SelectedLeague));
_SelectedLeague = null;
}
}
}
有时候这似乎能够按照我所希望的工作。它将导航到新的DivisionsPage并隐藏主页面。在iOS和UWP上似乎运行良好,但在Android上出现崩溃,具体情况如下:
[0:] Server Returned 34 divisions
[0:] Navigating to DivisionsPage with LeagueID 12
[0:] UpdatePoolRankings: Called GetDivisionsAsync
03-23 02:40:52.151 W/Mono ( 6249): The request to load the assembly System.Core v4.0.0.0 was remapped to v2.0.5.0
03-23 02:40:52.151 D/Mono ( 6249): Unloading image System.Core.dll [0x99db7700].
03-23 02:40:52.151 D/Mono ( 6249): Image addref System.Core[0xaec169a0] -> System.Core.dll[0x9d166d00]: 11
03-23 02:40:52.151 D/Mono ( 6249): Config attempting to parse: 'System.Core.dll.config'.
03-23 02:40:52.151 D/Mono ( 6249): Config attempting to parse: '/Users/builder/data/lanes/4009/f3074d2c/source/monodroid/builds/install/mono-x86/etc/mono/assemblies/System.Core/System.Core.config'.
03-23 02:40:52.152 W/Mono ( 6249): The request to load the assembly System.Core v4.0.0.0 was remapped to v2.0.5.0
03-23 02:40:52.152 D/Mono ( 6249): Unloading image System.Core.dll [0x99db7700].
03-23 02:40:52.152 D/Mono ( 6249): Image addref System.Core[0xaec169a0] -> System.Core.dll[0x9d166d00]: 12
03-23 02:40:52.152 D/Mono ( 6249): Config attempting to parse: 'System.Core.dll.config'.
03-23 02:40:52.152 D/Mono ( 6249): Config attempting to parse: '/Users/builder/data/lanes/4009/f3074d2c/source/monodroid/builds/install/mono-x86/etc/mono/assemblies/System.Core/System.Core.config'.
03-23 02:40:52.383 D/Mono ( 6249): [0x9b5bf930] hill climbing, change max number of threads 4
[0:] Server Returned 3 divisions
03-23 02:40:52.421 F/ ( 6249): * Assertion at /Users/builder/data/lanes/4009/f3074d2c/source/mono/mono/metadata/sgen-tarjan-bridge.c:1139, condition `xref_count == xref_index' not met
03-23 02:40:52.421 F/libc ( 6249): Fatal signal 6 (SIGABRT), code -6 in tid 6249 (ClubApp.Droid)
InspectorDebugSession(21): Disposed
InspectorDebugSession(21): HandleTargetEvent: TargetExited
如果需要更多细节,请告诉我,谢谢!