How to check if JSON is null in swift?

if ((nullObject as? NSNull) == nil)  {
        ...
       }

Try something like this:

Swift code:

if let outcome = dict["outcome_status"] as? NSDictionary {
    //Now you know that you received a dictionary(another json doc) and is not 'nil'
    //'outcome' is only valid inside this if statement

    if let category = outcome["category"] as? String {
        //Here you received string 'category'
        outcomeStatusLabel.text = category
        outcomeStatusLabel.font = UIFont.systemFontOfSize(14.0)
        outcomeStatusLabel.numberOfLines = 0
    }

    if let date = outcome["date"] as? String {
        //Here you received string 'date'
        outcomeDateLabel.text = date
        outcomeDateLabel.font = UIFont.systemFontOfSize(14.0)
        outcomeDateLabel.numberOfLines = 0
    }
}

This is a safe way to work with Json.