NSData和结构体struct之间如何转换   

 

 

用处是当用NSNotification传递数据时需要这个转换，然后把NSData放到userInfo中。

// make a NSData object 

NSData *myData = [NSData dataWithBytes:&myPacketJoin length:sizeof(myPacketJoin)]; 

// make a new PacketJoin 

PacketJoin newJoin; 

[myData getBytes:&newJoin length:sizeof(newJoin)];

 

struct msg { 

        uint32_t msgtype;

        uint32_t param1;

        uint32_t param2;

    };

    struct msg a;

    

    a.msgtype = 123456;

    a.param1 = 12345;

    a.param2 = 12345;

   

    

    struct msg ba;

    NSData *msgData = [[NSData alloc]initWithBytes:&a length:sizeof(a)];

    [msgData getBytes:&ba length:sizeof(ba)];

    

    

    NSLog(@"a:%u", ba.msgtype);

    NSLog(@"ba:%u", a.msgtype );