#define ITMS_SANDBOX_VERIFY_RECEIPT_URL     @"https://sandbox.itunes.apple.com/verifyReceipt"

#pragma mark - VerifyFinishedTransaction

-(void)verifyFinishedTransaction:(SKPaymentTransaction *)transaction{

    if(transaction.transactionState == SKPaymentTransactionStatePurchased){

        NSString *transactionIdentifier =  transaction.transactionIdentifier;

        NSData *transactionReceipt  = transaction.transactionReceipt;

        //将transactionIdentifer和加密后的transactionReceipt数据发送给server端

        NSString* receipent = [NSString stringWithFormat:@"%s", transactionReceipt.bytes];

        NSLog(@"receipent = %@", receipent);

        // 在app上做验证, 仅用于测试

        NSString *payload = [NSString stringWithFormat:@"{\"receipt-data\" : \"%@\", \"password\" : \"%@\"}",

                             receipent, transactionIdentifier];

        NSData *payloadData = [payload dataUsingEncoding:NSUTF8StringEncoding];

        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:ITMS_SANDBOX_VERIFY_RECEIPT_URL]];

        [request setHTTPMethod:@"POST"];

        [request setHTTPBody:payloadData];

        NSError* err;

        NSURLResponse *theResponse = nil;

        NSData *data=[NSURLConnection sendSynchronousRequest:request

                                           returningResponse:&theResponse

                                                       error:&err];

        NSError *jsonParsingError = nil;

        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&jsonParsingError];

        NSLog(@"%@", dict);

        NSLog(@"done");

        }

}