我用Xamarin有很多困难。
基本上所有我想做的是POST和抓取一些JSON到/从一个web服务器，然后调用一个事件，气泡通过委托(最终将是一个)UI更改事件(目前它只是一个调试。writeline调用).
我有两个PCL库，一个是"核心"，另一个是核心引用的库，一个WPF应用程序和一个OS X应用程序- WPF应用程序工作良好。我还使用了MVVMCross
起初，我尝试使用一个预先存在的类，我使用HTTPWebRequest，它工作得很好，第一个按钮点击(触发这个调用)。在第二个按钮上点击OS X应用程序崩溃。我试着切换到HttpClient，没有骰子。
在阅读了这个线程:https://bugzilla.xamarin.com/show_bug.cgi?id=19906之后，我尝试了使用接口将OS X应用程序的HTTP类切换到NSUrlConnection的本地实现。
现在这是我发现自己的情况:如果我有一个NSUrlConnection异步请求与一个匿名函数传递给它，它的工作永远点击后点击如果我把它拿出来，并调用FireEvent()函数，它只是引发事件(这可能会引发更多的事件链)，然后它永远工作，点击后点击如果我同时拥有匿名异步函数和FireEvent，那么在第三次点击触发该函数的按钮时，它会引发本机崩溃。
如果我取出所有异步的东西，它会工作得很好，但这不是理想的。
任何想法?我已经无计可施了。
public void ExecuteAsync()
{
var request = new NSUrlRequest(new NSUrl("http://www.example.com"));
asyncRunning = true;
NSUrlConnection.SendAsynchronousRequest(request, NSOperationQueue.MainQueue, delegate(NSUrlResponse response, NSData data, NSError error) {
var responseStr = data.ToString();
var blah = new HttpResponseCompleteEventArgs("{TESTJSONThatIveRemovedForReadability}");
System.Diagnostics.Debug.WriteLine("Inside IsMainThread: " + NSThread.IsMain.ToString());
response.InvokeOnMainThread ( delegate {
FireEvent(blah);
System.Diagnostics.Debug.WriteLine("Inside IsMainThread invoke: " + NSThread.IsMain.ToString());
});
});
System.Diagnostics.Debug.WriteLine("Outside IsMainThread: " + NSThread.IsMain.ToString());
}
和崩溃
Stacktrace:
at <unknown> <0xffffffff>
at (wrapper managed-to-native) MonoMac.AppKit.NSApplication.NSApplicationMain (int,string[]) <IL 0x0009d, 0xffffffff>
at MonoMac.AppKit.NSApplication.Main (string[]) [0x00041] in /Users/builder/data/lanes/xamcore-lion-1.8-branch/b8b75fd4/source/xamcore/src/AppKit/NSApplication.cs:105
at FreshlySqueezed.Mac.MainClass.Main (string[]) [0x00007] in /Users/blah/Development/Development/FreshlySqueezed/FreshlySqueezed.Mac/Main.cs:14
at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>
Native stacktrace:
Debug info from gdb:
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quProcess 2693 stopped
* thread #1: tid = 0x1e2f7, 0x91b0cfed libsystem_kernel.dylib`__wait4 + 5, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
thread #2: tid = 0x1e30e, 0x91b0d992 libsystem_kernel.dylib`kevent64 + 10, queue = 'com.apple.libdispatch-manager'
thread #3: tid = 0x1e30f, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
thread #4: tid = 0x1e310, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
thread #5: tid = 0x1e311, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
thread #6: tid = 0x1e314, 0x91b07fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10
thread #7: tid = 0x1e315, 0x91b0ca26 libsystem_kernel.dylib`__recvfrom + 10
thread #8: tid = 0x1e32c, 0x91b07f7a libsystem_kernel.dylib`mach_msg_trap + 10
thread #9: tid = 0x1e32e, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
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qu* thread #1: tid = 0x1e2f7, 0x91b0cfed libsystem_kernel.dylib`__wait4 + 5, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
* frame #0: 0x91b0cfed libsystem_kernel.dylib`__wait4 + 5
frame #1: 0x92c46ec5 libsystem_c.dylib`waitpid$UNIX2003 + 48
frame #2: 0x018ab5f9 libmono-2.0.dylib`mono_handle_native_sigsegv(signal=11, ctx=0x006e1fe0) + 489 at mini-exceptions.c:2305
frame #3: 0x018fd9d5 libmono-2.0.dylib`mono_arch_handle_altstack_exception(sigctx=0x006e1fe0, fault_addr=0x608962a8, stack_ovf=0) + 149 at exceptions-x86.c:1170
frame #4: 0x01804351 libmono-2.0.dylib`mono_sigsegv_signal_handler(_dummy=11, info=0x006e1fa0, context=0x006e1fe0) + 369 at mini.c:6842
frame #5: 0x94fd1deb libsystem_platform.dylib`_sigtramp + 43
thread #2: tid = 0x1e30e, 0x91b0d992 libsystem_kernel.dylib`kevent64 + 10, queue = 'com.apple.libdispatch-manager'
frame #0: 0x91b0d992 libsystem_kernel.dylib`kevent64 + 10
frame #1: 0x9a415899 libdispatch.dylib`_dispatch_mgr_invoke + 238
frame #2: 0x9a415532 libdispatch.dylib`_dispatch_mgr_thread + 52
thread #3: tid = 0x1e30f, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #0: 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x91cfbdcf libsystem_pthread.dylib`_pthread_wqthread + 372
thread #4: tid = 0x1e310, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #0: 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x91cfbdcf libsystem_pthread.dylib`_pthread_wqthread + 372
thread #5: tid = 0x1e311, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #0: 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x91cfbdcf libsystem_pthread.dylib`_pthread_wqthread + 372
thread #6: tid = 0x1e314, 0x91b07fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10
frame #0: 0x91b07fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10
frame #1: 0x01a1891e libmono-2.0.dylib`mono_sem_wait(sem=<unavailable>, alertable=<unavailable>, sem=0x01b1ac20, alertable=1) + 30 at mono-semaphore.c:121
frame #2: 0x019c43ea libmono-2.0.dylib`finalizer_thread(unused=0x00000000) + 74 at gc.c:1073
frame #3: 0x0199c654 libmono-2.0.dylib`start_wrapper [inlined] start_wrapper_internal(data=0x00193bd0) + 442 at threads.c:647
frame #4: 0x0199c49a libmono-2.0.dylib`start_wrapper(data=0x00193bd0) + 26 at threads.c:692
frame #5: 0x01a1de1d libmono-2.0.dylib`inner_start_thread(arg=0xbffff2c0) + 253 at mono-threads-posix.c:94
frame #6: 0x01a3eebd libmono-2.0.dylib`GC_start_routine(arg=0x006e2f60) + 93 at pthread_support.c:1502
frame #7: 0x91cfa5fb libsystem_pthread.dylib`_pthread_body + 144
frame #8: 0x91cfa485 libsystem_pthread.dylib`_pthread_start + 130
thread #7: tid = 0x1e315, 0x91b0ca26 libsystem_kernel.dylib`__recvfrom + 10
frame #0: 0x91b0ca26 libsystem_kernel.dylib`__recvfrom + 10
frame #1: 0x92c470c9 libsystem_c.dylib`recv$UNIX2003 + 54
frame #2: 0x018d58c0 libmono-2.0.dylib`socket_transport_recv(buf=0xb039aeed, len=11) + 160 at debugger-agent.c:1085
frame #3: 0x018d1c8d libmono-2.0.dylib`debugger_thread(arg=0x00000000) + 21485 at debugger-agent.c:1475
frame #4: 0x01a1de1d libmono-2.0.dylib`inner_start_thread(arg=0xbffff2c0) + 253 at mono-threads-posix.c:94
frame #5: 0x01a3eebd libmono-2.0.dylib`GC_start_routine(arg=0x006e2f60) + 93 at pthread_support.c:1502
frame #6: 0x91cfa5fb libsystem_pthread.dylib`_pthread_body + 144
frame #7: 0x91cfa485 libsystem_pthread.dylib`_pthread_start + 130
thread #8: tid = 0x1e32c, 0x91b07f7a libsystem_kernel.dylib`mach_msg_trap + 10
frame #0: 0x91b07f7a libsystem_kernel.dylib`mach_msg_trap + 10
frame #1: 0x91b0716c libsystem_kernel.dylib`mach_msg + 68
frame #2: 0x9bea0bf9 CoreFoundation`__CFRunLoopServiceMachPort + 169
frame #3: 0x9bea01d1 CoreFoundation`__CFRunLoopRun + 1393
frame #4: 0x9be9f9ea CoreFoundation`CFRunLoopRunSpecific + 394
frame #5: 0x9be9f84b CoreFoundation`CFRunLoopRunInMode + 123
frame #6: 0x90de9b88 AppKit`_NSEventThread + 283
frame #7: 0x91cfa5fb libsystem_pthread.dylib`_pthread_body + 144
frame #8: 0x91cfa485 libsystem_pthread.dylib`_pthread_start + 130
thread #9: tid = 0x1e32e, 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #0: 0x91b0d046 libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x91cfbdcf libsystem_pthread.dylib`_pthread_wqthread + 372
Executing commands in '/tmp/mono-gdb-commands.J45EfM'.
(lldb) process attach --pid 2693
Process 2693 stopped
有人知道吗?我一头雾水。
谢谢
所以经过几个小时的挠头，我似乎偶然发现了解决方案。
从一开始，我就怀疑这与垃圾收集有关，或者事件失去了它的绑定，因为在我的任何代码被点击第三次后，应用程序崩溃了，从阅读Xamarin/OS X的其他stackoverflow问题，我的症状听起来像一个过度渴望的垃圾收集器。
所以一开始我以为每次我从web服务器得到响应时都会引发一个事件，事件已经冒泡到ViewModel，所以本质上它在OSX项目中冒泡到ViewController。目的是尝试使用此事件在每次单击后重新绑定按钮绑定-但是我尝试使用空事件处理程序运行它，并且我发现它修复了初始问题!
尽管ViewController已经通过这个有一个对ViewModel的引用。ViewModel，似乎OS X/XamMac是过于急于和处置ViewModel，因此把应用程序到它的膝盖。有趣的是，我只发现添加和处理一个事件来解决这个问题，试图分配这个。对另一个类变量的ViewModel没有影响。
下面是修复它的代码:
在视图模型中我添加了这个:
public event System.EventHandler GoCommandFinished;
public void CallbackFromWebRequest(SqueezeBase value){
System.Diagnostics.Debug.WriteLine("hmmm");
Hello = "whey?" + x;
if (GoCommandFinished != null) {
GoCommandFinished (null, null);
}
}
在OS X侧的视图控制器中我将这个添加到ViewDidLoad:
((FirstViewModel)this.ViewModel).GoCommandFinished += GoCommandFinished;
，然后创建一个空函数来处理:
private void GoCommandFinished(object sender, EventArgs e){
}
和volia !我很想知道一种更干净的方法来解决这个问题，因为这对我来说感觉很粗糙……但现在，我不在乎，它有效!但如果有Xamarin的人能解释一下如何更优雅地平息垃圾收集，那就太好了!
谢谢