二、MAC上通过USB传输信息

1、导入依赖头文件

#include <IOKit/hid/IOHIDLib.h>
2、初始化IOHIDManager
IOHIDManagerRef managerRef = IOHIDManagerCreate(kCFAllocatorDefault, kIOHIDOptionsTypeNone);
3、进行配对设置，可以过滤其他USB设备。
1）无配对设备
IOHIDManagerSetDeviceMatching(HIDManager, NULL);
2）单类设备配对
NSMutableDictionary* dict= [NSMutableDictionary dictionary];
[dict setValue:pid forKey:[NSString stringWithCString:kIOHIDProductIDKey encoding:NSUTF8StringEncoding]];
[dict setValue:vid forKey:[NSString stringWithCString:kIOHIDVendorIDKey encoding:NSUTF8StringEncoding]];
IOHIDManagerSetDeviceMatching(managerRef, (__bridge CFMutableDictionaryRef)dict);
3）多种设备配对设置
NSMutableArray *arr = [NSMutableArray array];
[arr addObject:dict];
IOHIDManagerSetDeviceMatchingMultiple(managerRef, (__bridge CFMutableArrayRef)arr);
4、注册插拔设备的callback
    //注册插入callback
    IOHIDManagerRegisterDeviceMatchingCallback(managerRef, &Handle_DeviceMatchingCallback, NULL);
    //注册拔出callback
    IOHIDManagerRegisterDeviceRemovalCallback(managerRef, &Handle_DeviceRemovalCallback, NULL);
5、加入RunLoop
IOHIDManagerScheduleWithRunLoop(managerRef, CFRunLoopGetMain(), kCFRunLoopDefaultMode);
6、打开IOHIDManager
   IOReturn ret = IOHIDManagerOpen(managerRef, kIOHIDOptionsTypeNone);
    if (ret == kIOReturnSuccess) {
      NSLog(@"IOHIDManager打开成功");
    }
7、实现插拔callback
static void Handle_DeviceMatchingCallback(void *inContext,IOReturn inResult,void *inSender,IOHIDDeviceRef inIOHIDDeviceRef) {
      NSLog(@"插入：%p",(void *)inIOHIDDeviceRef);
}
static void Handle_DeviceRemovalCallback(void *inContext,IOReturn inResult,void *inSender,IOHIDDeviceRef inIOHIDDeviceRef) {
      NSLog(@"拔出：%p设备",(void *)inIOHIDDeviceRef);
}
8、插入设备获取到IOHIDDeviceRef inIOHIDDeviceRef后，打开IOHIDDeviceRef。
    IOOptionBits options = 0;
    IOReturn ret = IOHIDDeviceOpen(inIOHIDDeviceRef,options);
    if (ret == kIOReturnSuccess) {
        NSLog(@"打开成功");
    }
9、注册的接收数据callback。
IOHIDDeviceRegisterInputReportCallback(inIOHIDDeviceRef, (uint8_t*)inputbuffer, 64, MyInputCallback, NULL);
10、实现接收数据callback方法，即可接收数据。
static void MyInputCallback(void* context, IOReturn result, void* sender, IOHIDReportType type, uint32_t reportID, uint8_t *report,CFIndex reportLength) {
     RobotPenUSBLog(@"%s",report);
}
11、向USB设备发送指令。
IOReturn ret = IOHIDDeviceSetReport(inIOHIDDeviceRef, kIOHIDReportTypeOutput, 0, (uint8_t*)buffer, length);
    if (ret != kIOReturnSuccess) {
         NSLog(@"指令发送失败");
    }
12、断开设备
IOReturn ret = IOHIDDeviceClose(inIOHIDDeviceRef,0L);
  if (ret == kIOReturnSuccess) {
     NSLog(@"断开成功");

    }