iOS开源项目：UIDevice-with-UniqueIdentifier-for-iOS-5

用于替代系统UDID的方法。

https://github.com/gekitz/UIDevice-with-UniqueIdentifier-for-iOS-5

1、使用方法：

　　 UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
    label.numberOfLines = ;
    label.textAlignment = UITextAlignmentCenter;
    label.text = [NSString stringWithFormat:@"Unique Device Identifier:\n%@",
                  [[UIDevice currentDevice] uniqueDeviceIdentifier]];

    [self.view addSubview:label];
    [label release];

    label = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
    label.numberOfLines = ;
    label.textAlignment = UITextAlignmentCenter;
    label.text = [NSString stringWithFormat:@"Unique GLOBAL Device Identifier:\n%@",
                  [[UIDevice currentDevice] uniqueGlobalDeviceIdentifier]];

    [self.view addSubview:label];
    [label release];

只需要调用

[[UIDevice currentDevice] uniqueDeviceIdentifier]//Bundle ID + MAC address，可以区分同一设备，不同App

[[UIDevice currentDevice] uniqueGlobalDeviceIdentifier]// MAC address设备表示，所有App都相同

2、实现原理：

- (NSString *) uniqueDeviceIdentifier{
    NSString *macaddress = [[UIDevice currentDevice] macaddress];
    NSString *bundleIdentifier = [[NSBundle mainBundle] bundleIdentifier];

    NSString *stringToHash = [NSString stringWithFormat:@"%@%@",macaddress,bundleIdentifier];
    NSString *uniqueIdentifier = [stringToHash stringFromMD5];

    return uniqueIdentifier;
}

- (NSString *) uniqueGlobalDeviceIdentifier{
    NSString *macaddress = [[UIDevice currentDevice] macaddress];
    NSString *uniqueIdentifier = [macaddress stringFromMD5];

    return uniqueIdentifier;
}

首先要获取mac地址，这东西其实不复杂，所以不要被吓着了。就是调用一下操作系统底层获取mac地址的方法就行，把这段代码贴出来以防以后用着的时候忘了：

- (NSString *) macaddress{

    int                 mib[];
    size_t              len;
    char                *buf;
    unsigned char       *ptr;
    struct if_msghdr    *ifm;
    struct sockaddr_dl  *sdl;

    mib[] = CTL_NET;
    mib[] = AF_ROUTE;
    mib[] = ;
    mib[] = AF_LINK;
    mib[] = NET_RT_IFLIST;

    if ((mib[] = if_nametoindex("en0")) == ) {
        printf("Error: if_nametoindex error\n");
        return NULL;
    }

    if (sysctl(mib, , NULL, &len, NULL, ) < ) {
        printf("Error: sysctl, take 1\n");
        return NULL;
    }

    if ((buf = malloc(len)) == NULL) {
        printf("Could not allocate memory. error!\n");
        return NULL;
    }

    if (sysctl(mib, , buf, &len, NULL, ) < ) {
        printf("Error: sysctl, take 2");
        free(buf);
        return NULL;
    }

    ifm = (struct if_msghdr *)buf;
    sdl = (struct sockaddr_dl *)(ifm + );
    ptr = (unsigned char *)LLADDR(sdl);
    NSString *outstring = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",
                           *ptr, *(ptr+), *(ptr+), *(ptr+), *(ptr+), *(ptr+)];
    free(buf);

    return outstring;
}

然后就是生成16进制的标识符了

- (NSString *) stringFromMD5{

    if(self == nil || [self length] == )
        return nil;

    const char *value = [self UTF8String];
    NSString *string = [NSString stringWithUTF8String:value];
    NSLog(@"value = %@", string);
    unsigned char outputBuffer[CC_MD5_DIGEST_LENGTH];
    CC_MD5(value, strlen(value), outputBuffer);

    NSMutableString *outputString = [[NSMutableString alloc] initWithCapacity:CC_MD5_DIGEST_LENGTH * ];
    for(NSInteger count = ; count < CC_MD5_DIGEST_LENGTH; count++){
        [outputString appendFormat:@"%02x",outputBuffer[count]];
    }

    return [outputString autorelease];
}