Search code examples
c#jsonencodingapple-push-notificationspushsharp

Encoding with APNS Push in C#

I'm using PushSharp to handle push notifications for iOS.

Everything went well until I realized the way I'm handling the push isn't too powerful:

apnsBroker.QueueNotification(new ApnsNotification {

            DeviceToken = device.DeviceIdentifier,
            Payload = JObject.Parse("{\"aps\":{\"alert\" : {\"title\" : \"" + title 
            + "\", \"body\" : \"" + body + "\"}, \"badge\":" + badgeCount + "}, " + 
            "\"entity_id\" : \"" + entityId + "\", \"category_id\" : \"" + categoryId + "\", \"sub_id\" : \"" + subId
            + "\"}")
        });

Edit / Update One of the parameters I am trying is \t\ud83d\uddbc️\ (basically I wanted to pass in the unicode character of the picture frame emoji, so it can be rendered in the APNS alert). It is breaking currently.

I am sending that in C# like this: @"\t\ud83d\uddbc️\"

So as you can see, I'm rendering out the JSON Payload and this framework takes in a JObject. The problem, as I immediately assumed during my code review, is that if any of those parameters above (title, body, etc) end up being strings such as { or " or { etc that it will "break" the JSON because JObject can't parse that as valid JSON.

What do you think I should do in this case? Do I have to encode it and I suppose the only drawback would be I have backslashes or something in the encoding? Any recommendations to permit the user input (title and body can be free form text so anything is possible).

Thank you in advance for any advice!

EDIT

Thank you again Zero for your help.

var escapedString = JsonConvert.ToString(normalString);

saved the day. It's important to note that if you are using this, then escapedString should not be wrapped in ""'s since it will already be escaped (as he mentioned below).

Solution

  • As long as your variables are quoted (inside ") there's no need to escape braces ({ and })

    As for breaking the quote (having ") inside variables, you could do something like this:

    //Escapes quotes
param = param.Replace(@"""", @"\""");

    You also need to escape the escape char itself \

    //Escapes backslash
param = param.Replace(@"\", @"\\");

    Also, here are all valid escapes.

    If you're using Newtonsoft.Json they have a method to do this for you.

    Example usage below or take a look here. Be aware this will add quotes to the string for you.

    //Or use the return value inline with interpolation "$" or concatenation "+"
var escapedString = JsonConvert.ToString(normalString);