IOKit 设备添加/删除通知 - 只触发一次？答案

【问题标题】：IOKit device adding/removal notifications - only fire once?IOKit 设备添加/删除通知 - 只触发一次？
【发布时间】：2012-07-24 09:45:09
【问题描述】：

我一直在尝试在添加或删除特定 USB 设备时收到通知。我已阅读“从应用程序访问硬件”文档并有一个简单的演示应用程序，主要基于该文档中提供的代码。

第一次添加或删除设备时它会起作用，但之后我的回调就不会被调用。我不知道为什么？谁能发现我哪里出错了？

(xcode 项目，如果你想测试) http://monkeyfood.com/testIOKitNOtificaiton.zip

谢谢。

//
//  AppDelegate.m
//  testIOKitNotification
//
//  Created by Diggory Laycock on 23/07/2012.
//  Copyright (c) 2012 MonkeyFood.com. All rights reserved.
//

#import "AppDelegate.h"

@implementation AppDelegate


//          Arduino USB info
#define     matchVendorID           0x2341      
#define     matchProductID          0x0043


#pragma mark -
#pragma mark C Callback functions
#pragma mark -

void usbDeviceAppeared(void *refCon, io_iterator_t iterator){
    NSLog(@"Matching USB device appeared");
}
void usbDeviceDisappeared(void *refCon, io_iterator_t iterator){
    NSLog(@"Matching USB device disappeared");
}


@synthesize window = _window;


#pragma mark -
#pragma mark Application Methods
#pragma mark -



- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    io_iterator_t newDevicesIterator;
    io_iterator_t lostDevicesIterator;

    newDevicesIterator = 0;
    lostDevicesIterator = 0;
    NSLog(@" ");

    NSMutableDictionary *matchingDict = (__bridge NSMutableDictionary *)IOServiceMatching(kIOUSBDeviceClassName);

    if (matchingDict == nil){
        NSLog(@"Could not create matching dictionary");
        return;
    }
    [matchingDict setObject:[NSNumber numberWithShort:matchVendorID] forKey:(NSString *)CFSTR(kUSBVendorID)];
    [matchingDict setObject:[NSNumber numberWithShort:matchProductID] forKey:(NSString *)CFSTR(kUSBProductID)];

    //  Add notification ports to runloop
    IONotificationPortRef notificationPort = IONotificationPortCreate(kIOMasterPortDefault);
    CFRunLoopSourceRef notificationRunLoopSource = IONotificationPortGetRunLoopSource(notificationPort);
    CFRunLoopAddSource([[NSRunLoop currentRunLoop] getCFRunLoop], notificationRunLoopSource, kCFRunLoopDefaultMode);

    kern_return_t err;
    err = IOServiceAddMatchingNotification(notificationPort, 
                                           kIOMatchedNotification, 
                                           (__bridge CFDictionaryRef)matchingDict, 
                                           usbDeviceAppeared, 
                                           (__bridge void *)self, 
                                           &newDevicesIterator);
    if (err)
    {
        NSLog(@"error adding publish notification");
    }
    [self matchingDevicesAdded: newDevicesIterator];


    NSMutableDictionary *matchingDictRemoved = (__bridge NSMutableDictionary *)IOServiceMatching(kIOUSBDeviceClassName);

    if (matchingDictRemoved == nil){
        NSLog(@"Could not create matching dictionary");
        return;
    }
    [matchingDictRemoved setObject:[NSNumber numberWithShort:matchVendorID] forKey:(NSString *)CFSTR(kUSBVendorID)];
    [matchingDictRemoved setObject:[NSNumber numberWithShort:matchProductID] forKey:(NSString *)CFSTR(kUSBProductID)];


    err = IOServiceAddMatchingNotification(notificationPort, 
                                           kIOTerminatedNotification, 
                                           (__bridge CFDictionaryRef)matchingDictRemoved, 
                                           usbDeviceDisappeared, 
                                           (__bridge void *)self, 
                                           &lostDevicesIterator);
    if (err)
    {
        NSLog(@"error adding removed notification");
    }
    [self matchingDevicesRemoved: lostDevicesIterator];


    //      CFRunLoopRun();
    //      [[NSRunLoop currentRunLoop] run];

}

#pragma mark -
#pragma mark ObjC Callback functions
#pragma mark -

- (void)matchingDevicesAdded:(io_iterator_t)devices
{
    io_object_t thisObject;
    while ( (thisObject = IOIteratorNext(devices))) {
        NSLog(@"new Matching device added ");
        IOObjectRelease(thisObject); 
    } 

}


- (void)matchingDevicesRemoved:(io_iterator_t)devices
{
    io_object_t thisObject;
    while ( (thisObject = IOIteratorNext(devices))) {
        NSLog(@"A matching device was removed ");
        IOObjectRelease(thisObject); 
    } 

}


@end

【问题讨论】：

标签： macos cocoa iokit

【解决方案1】：

我已经找出了问题所在 - 我没有对 C 回调中的迭代器做任何事情。一个愚蠢的错误！

【讨论】：

【解决方案2】：

我有点晚了，因为有一个可接受的答案，但要解决这个问题，您需要在回调中迭代匹配的设备迭代器。但这样做并非易事，所以这里是实现这一目标的代码，因为回调是一个 C 函数，并且您希望将它桥接到您的 Objective C 方法。

void usbDeviceAppeared(void *refCon, io_iterator_t iterator){
    NSLog(@"Matching USB device appeared");
    SerialMonitor *monitor = (__bridge SerialMonitor *)refCon;
    [monitor matchingDevicesAdded:iterator];
    [monitor reload];
}

void usbDeviceDisappeared(void *refCon, io_iterator_t iterator){
    NSLog(@"Matching USB device disappeared");
    SerialMonitor *monitor = (__bridge SerialMonitor *)refCon;
    [monitor matchingDevicesRemoved:iterator];
    [monitor reload];
}

SerialMonitor 是我的 USB 设备管理器类，reload 是一种执行适当 USB 设备初始化（获取功能报告和交换数据）的方法。

【讨论】：