#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");
        }
}