Modify an array of json objects

I have a list of json objects which I need to modify the values within each of them. I'm accessing this list of json objects in the below piece of code:

            if let json = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
            
            let objects = json["data"] as? [String: Any]
            if let accounts = objects?["accounts"] as? [[String:Any]]{
                
                print("Accounts: \(accounts)")
                for account in accounts {
                    account["balance"] = nil
                }
            }
            
            modifiedData = try JSONSerialization.data(withJSONObject: json, options: [])
        }

But the accounts array is immutable. I've tried casting to NSMutableDictionary and NSMutableArray but can't seem to get it to work. Does anyone have any tips?

You need to work with var declared variables instead and access the accounts array by index instead

if var json = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
    var objects = json["data"] as? [String: Any]
    if var accounts = objects?["accounts"] as? [[String:Any]] {
        for index in 0..<accounts.count {
            accounts[index]["balance"] = 0
        }
        objects?["accounts"] = accounts
    }
    json["data"] = objects
}