Xamarin.iOS构建遇两类问题：调用报错与AOT编译失败求助

Hey there, let's break down and fix these two frustrating build problems you're facing:

1. Crash When Using "Link All" Linker Behavior #

Error Message: #

You MUST invoke LoadApplication () before calling base.FinishedLaunching ()

What's Going On: #

When you set linker behavior to Link All, Xamarin's linker aggressively removes code it thinks isn't being used. In most cases, either your FinishedLaunching method has the wrong execution order, or the linker has stripped critical Xamarin.Forms initialization code by mistake.

Fixes to Try: #

• Verify Execution Order: Double-check your AppDelegate.cs to make sure LoadApplication runs before base.FinishedLaunching. Here's the correct structure:

  public override bool FinishedLaunching(UIApplication app, NSDictionary options)
  {
      global::Xamarin.Forms.Forms.Init();
      LoadApplication(new App()); // This line comes FIRST
      return base.FinishedLaunching(app, options);
  }
  

• Add Linker Hints: If the code order is correct but the linker still strips necessary code, create a LinkerPleaseInclude.cs file in your iOS project with these snippets to force the linker to keep critical Forms components:

  using Xamarin.Forms;
  
  public class LinkerPleaseInclude
  {
      public void Include(Application app)
      {
          app.PropertyChanged += (sender, e) => { };
      }
  
      public void Include(Page page)
      {
          page.Appearing += (sender, e) => { };
          page.Disappearing += (sender, e) => { };
      }
  }
  

  Alternatively, mark your App class and AppDelegate methods with the [Preserve(AllMembers = true)] attribute to prevent the linker from touching them.

2. MT3001 AOT Error When Using "Link Framework SDKs Only" #

Error Message: #

MT3001: Could not AOT the assembly. /Users/macmini01/Desktop/Per/RunningCode_Both/XXX_Mobile Sourcecode_2Apr2018/XXX/XXX.iOS/MTOUCH: Error MT3001: Could not AOT the assembly '/Users/m...

What's Going On: #

AOT (Ahead-of-Time) compilation failures usually stem from memory constraints, overly long file paths, outdated tooling, or incompatible third-party libraries. Your project path looks really long—this is a common culprit for AOT issues on macOS.

Fixes to Try: #

• Shorten Your Project Path: Move your entire project folder to a much shorter location, like /Users/macmini01/Desktop/XXX/. Long paths can confuse the AOT compiler and lead to file access errors.
• Clean & Rebuild From Scratch: Delete the bin and obj folders in your iOS project, restart Visual Studio for Mac, then rebuild the project. This clears out cached build artifacts that might be corrupted.
• Free Up Memory: AOT compilation is memory-heavy. Close any unnecessary apps (like browsers, video editors) to free up RAM. If your Mac has less than 8GB of RAM, consider upgrading or enabling virtual memory temporarily.
• Update Xamarin.iOS: Outdated versions of Xamarin.iOS often have AOT bugs. Head to Visual Studio for Mac's update manager and install the latest stable release.
• Check Third-Party Libraries: Some NuGet packages aren't fully compatible with AOT compilation. Try removing recently added libraries one by one to identify which one is causing the issue. You can then look for an updated version or a compatible alternative.

内容的提问来源于stack exchange，提问作者shiv