Saya menulis kode XAML dan C# di bawah ini untuk menyetel properti IsVisible
dari ActivityIndicator
ke True
di Android dan iOS. Kode C# di belakang kode mengikat properti yang sama ke properti IsBusy
dari konteks pengikatan di Windows. Kode ini berfungsi seperti yang diharapkan di semua platform.
# XAML Code
<ActivityIndicator x:Name="AI" IsEnabled="{Binding Path=IsBusy}" IsVisible="True" IsRunning="{Binding Path=IsBusy}"/>
# C# Code
if (Device.RuntimePlatform == Device.Windows)
{
AI.SetBinding(IsVisibleProperty, new Binding(nameof(ViewModel.IsBusy)));
}
Saya ingin memiliki perilaku yang sama hanya menggunakan XAML. Saya mencoba cuplikan kode di bawah ini tidak ada yang berhasil.
# 1
# Compiles. On Windows throws System.InvalidCastException:
# 'Unable to cast object of type 'Xamarin.Forms.Binding'
# to type 'System.Boolean'.'
<ActivityIndicator x:Name="AI" IsEnabled="{Binding Path=IsBusy}" IsRunning="{Binding Path=IsBusy}">
<ActivityIndicator.IsVisible>
<OnPlatform x:TypeArguments="x:Boolean">
<On Platform="Android" Value="True"/>
<On Platform="iOS" Value="True"/>
<On Platform="Windows" Value="{Binding Path=IsBusy}"/>
</OnPlatform>
</ActivityIndicator.IsVisible>
</ActivityIndicator>
# 2
# Doesn't compile. Gives an error saying "No property,
# bindable property, or event found for 'IsVisible'"
<ActivityIndicator x:Name="AI" IsEnabled="{Binding Path=IsBusy}" IsVisible="True" IsRunning="{Binding Path=IsBusy}">
<ActivityIndicator.IsVisible>
<OnPlatform x:TypeArguments="BindingBase">
<On Platform="Windows" Value="{Binding Path=IsBusy}"/>
</OnPlatform>
</ActivityIndicator.IsVisible>
</ActivityIndicator>
# 3
# Doesn't compile. Gives an error saying "No property,
# bindable property, or event found for 'IsVisible'"
<ActivityIndicator x:Name="AI" IsEnabled="{Binding Path=IsBusy}" IsVisible="True" IsRunning="{Binding Path=IsBusy}">
<ActivityIndicator.IsVisible>
<OnPlatform x:TypeArguments="Binding">
<On Platform="Windows" Value="{Binding Path=IsBusy}"/>
</OnPlatform>
</ActivityIndicator.IsVisible>
</ActivityIndicator>
# 4
# Compiles. On Windows throws System.InvalidCastException:
# 'Unable to cast object of type 'Xamarin.Forms.Binding'
# to type 'System.Boolean'.'
<ActivityIndicator x:Name="AI" IsEnabled="{Binding Path=IsBusy}" IsVisible="True" IsRunning="{Binding Path=IsBusy}">
<ActivityIndicator.IsVisible>
<OnPlatform x:TypeArguments="x:Boolean">
<On Platform="Windows">
<Binding Path="IsBusy" />
</On>
</OnPlatform>
</ActivityIndicator.IsVisible>
</ActivityIndicator>
Apakah mungkin melakukan ini di XAML?
IsVisible
dan elemenActivityIndicator.IsVisible
secara bersamaan seperti itu. - person Bradley Uffner   schedule 12.09.2017