In the process of developing an application, I have successfully implemented functionality to:
- Check for an internet connection;
- Receive a JSON file from the server and store the data in a file if the server is reachable;
- Read from the file if the connection to the server is unavailable.
Currently, I have managed to achieve connection checking, receiving JSON data, and storing it in an array.
The received JSON data has the following structure:
https://i.stack.imgur.com/pQSfA.png
Next, I convert this JSON data into an array of dictionaries in order to easily filter and access values based on their keys:
var rates = [ExchangeRates]() //instance of class Rate
var bnkDct = ["bank": "", "currency": "","buyrate": "", "sellrate": ""] //template
var indx : Int = 0 //index for iteration
for rate in jsonData{
let rate = ExchangeRates(data: rate as! NSDictionary)
rates.append(rate)
bnkDct["bank"] = rates[indx].bank
bnkDct["buyrate"] = rates[indx].buyRate
bnkDct["sellrate"] = rates[indx].sellRate
bnkDct["currency"] = rates[indx].currency
self.bankDict.append(bnkDct)
indx += 1
}
As a result, I now have an array that looks like this:
https://i.stack.imgur.com/uIx2f.png
My next step is to save this array to a file and be able to read from it. However, when I attempt to write data using the method below, I encounter an error:
let filePath = NSTemporaryDirectory() + "MyData.dat"
self.bankDict.writeToFile(filePath, automatically: true)
The error message states: "[(Dictionary)] doesn't have a writeToFile member." I also tried casting it as NSDictionary with no success. As an alternative, I attempted to use NSKeyedArchiver for writing data:
let filePath = NSTemporaryDirectory() + "MyData.dat"
NSKeyedArchiver.archiveRootObject(self.bankDict, toFile: filePath)
This approach results in a file with unexpected encoding:
https://i.stack.imgur.com/Ur0kU.png
When trying to read this file, I receive an error:
let newDictionary = NSKeyedUnarchiver.unarchiveObjectWithFile(filePath) as! [Dictionary <String,AnyObject> ]
The error message reads: "fatal error: unexpectedly found nil while unwrapping an Optional value." Additionally, upon inspection using the debugger, I noticed a large number of values in the newDictionary variable, indicating an issue with decoding the stored data.
I would appreciate any advice or suggestions on what might be incorrect in my approach or if I am utilizing improper practices in handling this task.