微信SDK是怎么能在App与微信之间传递数据的

微信SDK是怎么能在App与微信之间传递数据的。今天看了一下微信开放平台。下了SDK跑了跑。然后就产生了这个疑问。或者问iOS中有App之间传递数据的方法么。
主要是怎么传递的图片，一开始以为是他存在了相册里面，找了找没有看见。然后以为是上传到了tx自己的服务器然后。微信自己去找。然后断网试试。还是可以传过去。
具体方法贴一下
- (void) sendImageContent
{
//发送内容给微信
WXMediaMessage *message = [WXMediaMessage message];
[message setThumbImage:[UIImage imageNamed:@"res2.jpg"]];

WXImageObject *ext = [WXImageObject object];
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"res2" ofType:@"jpg"];
ext.imageData = [NSData dataWithContentsOfFile:filePath] ;

message.mediaObject = ext;

SendMessageToWXReq* req = [[[SendMessageToWXReq alloc] init]autorelease];
req.bText = NO;
req.message = message;
req.scene = _scene;

[WXApi sendReq:req];
}

- (void) RespImageContent
{
WXMediaMessage *message = [WXMediaMessage message];
[message setThumbImage:[UIImage imageNamed:@"res2.jpg"]];
WXImageObject *ext = [WXImageObject object];
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"res2" ofType:@"jpg"];
ext.imageData = [NSData dataWithContentsOfFile:filePath] ;
message.mediaObject = ext;

GetMessageFromWXResp* resp = [[[GetMessageFromWXResp alloc] init] autorelease];
resp.message = message;
resp.bText = NO;

[WXApi sendResp:resp];
}


大家有app之间传递数据的方法么？