问云代码在查找平均评等时返回空值。

EN

Parse.Cloud.define("calculateRating", function(request, response) {
    var query = new Parse.Query("Ratings");
    query.equalTo("placeName", request.params.place);
    query.find({
    success: function(results) {
    var sum = 0;
    for (var i = 0; i < results.length; ++i) {
        sum += results[i].get("rating");
    }
    response.success(sum / results.length);
    },
error: function() {
  response.error("movie lookup failed");
  }
});
});

 [PFCloud callFunctionInBackground:@"calculateRating"
                   withParameters:@{@"placeName":self.place}
                            block:^(NSNumber *ratings, NSError *error) {
                                if (!error) {
                                    NSLog(@"%@",ratings);
                                }
}];