如何解决找不到系统,找不到 Xamarin.Forms
严重性代码描述项目文件行抑制状态 错误 CS0246 找不到类型或命名空间名称“System”(您是否缺少 using 指令或程序集引用?) Beer Garden1 C:\Users\henry\source\repos\Beer Garden1\Beer Garden1\Beer Garden1\viewmodel \Loginviewmodel.cs 3 活动
严重性代码描述项目文件行抑制状态 错误 CS0246 找不到类型或命名空间名称“Xamarin”(您是否缺少 using 指令或程序集引用?) Beer Garden1 C:\Users\henry\source\repos\Beer Garden1\Beer Garden1\Beer Garden1\viewmodel \Loginviewmodel.cs 7 活动
我目前遇到上述错误,但不确定原因。我花了几个小时查看堆栈溢出和谷歌,但没有任何效果,
清洁解决方案、重建、重新加载构建无效。
修复visual studio无效
我很难过,请任何帮助将不胜感激!
using Beer_Garden1.Services;
using Beer_Garden1.View;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using Xamarin.Forms;
namespace Beer_Garden1.viewmodel
{
public class Loginviewmodel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public Command cmdLogin { get; set; }
public Command cmdCreateAccount { get; set; }
public Command cmdForgotPassword { get; set; }
public Command cmdsetting { get; set; }
ILoginService ilog = DependencyService.Get<ILoginService>();
public Loginviewmodel()
{
cmdLogin = new Command(gotoMainPage);
cmdCreateAccount = new Command(gotoCreateAccount);
cmdForgotPassword = new Command(gotoForgotPassword);
cmdsetting = new Command(gotoSetting);
}
private void gotoSetting(object obj)
{
App.Current.MainPage.Navigation.PushAsync(new SettingPage());
}
private void gotoForgotPassword(object obj)
{
App.Current.MainPage.Navigation.PushAsync(new ForgotPasswordPage());
}
private void gotoCreateAccount(object obj)
{
App.Current.MainPage.Navigation.PushAsync(new CreateAccountPage());
}
private void gotoMainPage(object obj)
{
if (ilog.login(UserName,Password))
{
App.Current.MainPage.Navigation.PushAsync(new MainPage());
}
else
{
LoginMessage = "Please enter a valid user name and password!";
TurnLoginMessage = true;
}
}
//-------------------------------------------------------------
private string userName;
public string UserName
{ get
{
return userName;
}
set
{
userName = value;
PropertyChanged?.Invoke(this,new PropertyChangedEventArgs("UserName"));
}
}
private string password;
public string Password
{
get
{
return password;
}
set
{
password = value;
PropertyChanged?.Invoke(this,new PropertyChangedEventArgs("Password"));
}
}
private string loginMessage;
public string LoginMessage
{
get
{
return LoginMessage;
} set
{
loginMessage = value;
PropertyChanged?.Invoke(this,new PropertyChangedEventArgs("LoginMessage"));
}
}
private bool turnLoginMessage = false;
public bool TurnLoginMessage
{
get
{
return turnLoginMessage;
}
set
{
turnLoginMessage = value;
PropertyChanged?.Invoke(this,new PropertyChangedEventArgs("TurnLoginMessage"));
}
}
}
}
_________________________________________________________________________________更新::
我设法修复了包源问题,它现在接受 xamarin.forms 和系统,但在 using System.Collections.Generic;
下抛出错误
using System.ComponentModel;
using System.Text;
恢复 NuGet 包时出现以下错误
NU1603: Beer Garden1.iOS depends on Xamarin.Forms (>= 4.8.0.1451) but Xamarin.Forms 4.8.0.1451 was not found. An approximate best match of Xamarin.Forms 5.0.0.2012 was resolved.
NU1102: Unable to find package System.Numerics.Vectors with version (>= 4.5.0)
- Found 2 version(s) in Microsoft Visual Studio Offline Packages [ Nearest version: 4.1.1 ]
NU1603: Beer Garden1.Android depends on Xamarin.Essentials (>= 1.5.3.2) but Xamarin.Essentials 1.5.3.2 was not found. An approximate best match of Xamarin.Essentials 1.6.1 was resolved.
NU1603: Beer Garden1.Android depends on Xamarin.Forms (>= 4.8.0.1451) but Xamarin.Forms 4.8.0.1451 was not found. An approximate best match of Xamarin.Forms 5.0.0.2012 was resolved.
NU1102: Unable to find package System.Numerics.Vectors with version (>= 4.5.0)
- Found 2 version(s) in Microsoft Visual Studio Offline Packages [ Nearest version: 4.1.1 ]
NuGet package restore Failed. Please see Error List window for detailed warnings and errors.
Time Elapsed: 00:00:00.1797576
解决方法
我最终解决了我的问题,我从 %appdata%
中删除了 NuGet 文件夹,然后在 VS 启动时使用其默认值重新创建,只需运行 NuGet 包还原,它删除了我的所有 98错误和我的 13 个警告。
我希望这对遇到相同问题的人有用,因为我自己很难在网上找到解决方案。
感谢大家的帮助!
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