Appending JSON data Swift - swift

Question

I am currently working on a school project where I need to be able to read, write and view information from a JSON file. For my assignment, I am attempting to build an app that is a dictionary where you can add your own words, definitions, etc.
I have been stuck on trying to write the new data to the JSON file without overwriting the old.
I also have an error on the last line that I am confused about.
Here is the code that I have so far.
func fileUrl() -> URL {
let documentURL = try!
FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
return documentURL.appendingPathComponent("data.json")
}
#IBAction func addWords(_ sender: UIButton) {
if let oldWords:[[String : String]] = getJsonData() as [[String:String]]? {
if let oldJson = try? JSONSerialization.data(withJSONObject: oldWords, options: []) {
// Add old words to JSON file
}
}
let data: [String:String] = [
"Name": nameField.text ?? "N/A",
"Part of Speech": posField.text ?? "N/A",
"Definition": defView.text ?? "N/A"
]
let url = fileUrl()
if let jsonData = try? JSONSerialization.data(withJSONObject: data, options: []) {
// Append data into JSON file
print(data)
nameField.text = ""
defView.text = ""
posField.text = ""
} else {
print("Failed to save")
}
}
func getJsonData() -> [[String:String]]? {
let url = fileUrl()
let responseData: Data? = try! Data(contentsOf: url)
if let responseData = responseData {
let json: String? = try? JSONSerialization.jsonObject(with: responseData, options: []) as? String
if let dictionary: [[String:String]]? = json as? [[String:String]]? {
return dictionary
}
}
} // Missing return in a function expected to return '[[String : String]]?' error
#IBAction func loadData(_ sender: UIButton) {
let url = fileUrl()
let responseData: Data? = try! Data(contentsOf: url)
if let responseData = responseData {
let json: Any? = try? JSONSerialization.jsonObject(with: responseData, options: [])
if let json = json {
let dictionary: [String: Any]? = json as? [String: Any]
if let dictionary = dictionary {
for names in dictionary {
let name: String = dictionary["Name"] as! String
let definition: String = dictionary["Definition"] as! String
let pos: String = dictionary["Part of Speech"] as! String
print(name, definition, pos)
textView.text = ("Name: \(name) (\(pos))\n Definition: \(definition)\n ")
}
}
}
}
}
I have been researching a way to add the JSON data but maybe I have been staring at the code so long that I am missing an easy fix.

Answer 1

There is no native way in swift, nor with a third party library to append json objects to a file.
What you need to do is, when you call getJsonData -- you save the whole contents of that JSON into a variable and append from there. I recommend looking at Daniel's answer for an easy extension for appending JSON together. Let me know if you need any more help!
Regarding your error on the last line - It is good practice to never force un-wrap variables. It's hard to tell given we can't see the JSON tree; but make sure you are accessing the correct spot. print(dictionary) your dictionary and try some debugging and/or create validation for your array.