Question

我成功创建了XPC服务，并通过从主应用程序发送消息与XPC服务进行通信。但我想知道的是，它是否可以启动从XPC服务到主应用程序的通信。 Apple documentation表示XPC是双向的。如果有人可以通过一个例子指出我正确的方向，我将不胜感激。

请注意，

我想从主应用程序启动XPC。
从主应用程序与XPC通信。
当某些事件发生时，XPC应该向主应用程序发送消息。

我在前两个方面取得了成功，但在第三个方面找不到任何资源。

感谢。：）

Answer 1

想出一切。以下应该是一个不错的例子：

ProcessorListener.h（包含在客户端和服务器中）：

@protocol Processor

- (void) doProcessing: (void (^)(NSString *response))reply;

@end

@protocol Progress

- (void) updateProgress: (double) currentProgress;
- (void) finished;

@end

@interface ProcessorListener : NSObject<NSXPCListenerDelegate, Processor>

@property (weak) NSXPCConnection *xpcConnection;

@end

ProcessorListener.m :(仅包含在服务器中）

#import "ProcessorListener.h"

@implementation ProcessorListener

- (BOOL)listener:(NSXPCListener *)listener shouldAcceptNewConnection:(NSXPCConnection *)newConnection
{
    [newConnection setExportedInterface: [NSXPCInterface interfaceWithProtocol:@protocol(Processor)]];
    [newConnection setExportedObject: self];
    self.xpcConnection = newConnection;

    newConnection.remoteObjectInterface = [NSXPCInterface interfaceWithProtocol: @protocol(Progress)];

    // connections start suspended by default, so resume and start receiving them
    [newConnection resume];

    return YES;
}

- (void) doProcessing: (void (^)(NSString *g))reply
{
    dispatch_async(dispatch_get_global_queue(0,0), ^{
      for(int index = 0; index < 60; ++index)
      {
         [NSThread sleepWithTimeInterval: 1];
         [[self.xpcConnection remoteObjectProxy] updateProgress: (double)index / (double)60 * 100];
      }

      [[self.xpcConnection remoteObjectProxy] finished];
    }

    // nil is a valid return value.
    reply(@"This is a reply!");
}

@end

MainApplication.m（您的主要应用）：

#import "ProcessorListener.h"

- (void) executeRemoteProcess
{
    // Create our connection
    NSXPCInterface * myCookieInterface = [NSXPCInterface interfaceWithProtocol: @protocol(Processor)];

    NSXPCConnection * connection = [[NSXPCConnection alloc] initWithServiceName: kServiceName];

    [connection setRemoteObjectInterface: myCookieInterface];

    connection.exportedInterface = [NSXPCInterface interfaceWithProtocol:@protocol(Progress)];
    connection.exportedObject = self;

    [connection resume];

    id<Processor> theProcessor = [connection remoteObjectProxyWithErrorHandler:^(NSError *err)
                       {
                           NSAlert *alert = [[NSAlert alloc] init];
                           [alert addButtonWithTitle: @"OK"];
                           [alert setMessageText: err.localizedDescription];
                           [alert setAlertStyle: NSWarningAlertStyle];

                           [alert performSelectorOnMainThread: @selector(runModal) withObject: nil waitUntilDone: YES];
                       }];

    [theProcessor doProcessing: ^(NSString * response)
     {
        NSLog(@"Received response: %@", response);
     }];
}

#pragma mark -
#pragma mark Progress

- (void) updateProgress: (double) currentProgress
{
    NSLog(@"In progress: %f", currentProgress);
}

- (void) finished
{
    NSLog(@"Has finished!");
}

@end

请注意，此代码是基于我的工作代码的精简版本。它可能无法100％编译，但显示了使用的关键概念。在该示例中，doProcessing运行异步以显示即使在初始方法返回并且已记录Progress之后，Received response: This is a reply!协议中定义的回调仍然执行。

如何从XPC帮助应用程序向主应用程序发送消息？

1 个答案: