problem in Parsing json in SWIFT for iOS developing - ios

Question

I have an Error in parsing JSON Format form an ASMX Web service,
My Code is
func getData() {
let url = URL(string: "http://192.168.11.188/getItems.asmx/theItems")
let theCategory = "ALL"
let theSubCategory = "ALL"
let postString = "theCategory=\(theCategory)&theSubCategory=\(theSubCategory)"
var request = URLRequest(url: url!)
request.httpMethod = "POST"
request.cachePolicy = NSURLRequest.CachePolicy.reloadIgnoringCacheData
request.httpBody = postString.data(using: String.Encoding.utf8)
URLSession.shared.dataTask(with: request) { (data, respons, error) in
if let error = error {
print("Error conning to server \(error)")
} else {
if let respons = respons as? HTTPURLResponse {
if respons.statusCode == 200 {
print(data!)
if let data = data {
do {
let json = try JSONDecoder().decode([ITEMS].self, from: data)
print(json)
} catch let parsingError {
print("Error parsing json \(parsingError)")
}
}
} else {
print("Error in responce code.... \(respons.statusCode)")
}
}
}
}.resume()
}
I am using the decoder struct in this code:
struct ITEMS: Codable {
let CODE:String
let CAT_ID:String
let SUB_ID:String
let PRODUCT_AR:String
let PRODUCT_EN:String
let OLD_PRICE:String
let NEW_PRICE:String
let UNIT:String
let BARCODE:String
let THE_DATE:String
let TIME:String
}
The JSON value is
{ ITEMS : [{"CODE":111,"CAT_ID":203,"SUB_ID":null,"PRODUCT_AR":"ITEM 1","PRODUCT_EN":"ITEM 1","OLD_PRICE":133.0035,"NEW_PRICE":109,"UNIT":null,"BARCODE":"328031002009","THE_DATE":"\/Date(1553673958397)\/","TIME":"11:05 AM"},
{"CODE":222,"CAT_ID":201,"SUB_ID":null,"PRODUCT_AR":"ITEM 2","PRODUCT_EN":"ITEM 2","OLD_PRICE":18.95,"NEW_PRICE":9.95,"UNIT":null,"BARCODE":"628103400012","THE_DATE":"\/Date(1553673958260)\/","TIME":"11:05 AM"}]}
but this code returns an Error
Error parsing JSON Error Domain=NSCocoaErrorDomain Code=3840 "JSON text did not start with array or object and option to allow fragments not set." UserInfo={NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}
What am I doing wrong?

Answer 1

as you are writing this,
let json = try JSONDecoder().decode([ITEMS].self, from: data)
it must ask for array of ITEMS to be parsed, but your JSON is just an object not an array (It starts with {ITEMS: [array_here]}).
For solving this issue, you need to make your struct like below and parse data into that object.
struct ITEMS: Codable {
let CODE:String
let CAT_ID:String
let SUB_ID:String
let PRODUCT_AR:String
let PRODUCT_EN:String
let OLD_PRICE:String
let NEW_PRICE:String
let UNIT:String
let BARCODE:String
let THE_DATE:String
let TIME:String
}
struct MyAPIData: Codable {
let ITEMS: [ITEMS]
}
Now parse data using below line of code,
let json = try JSONDecoder().decode(MyAPIData.self, from: data)

Answer 2

There were wrong types used in your struct, here is the fixed struct
struct ITEM: Codable {
let CODE:Int // not String
let CAT_ID:Int // not String
let SUB_ID:Int? // its null in JSON, use either Int? or String?
let PRODUCT_AR: String
let PRODUCT_EN: String
let OLD_PRICE:Double // not String
let NEW_PRICE:Double // not String
let UNIT:String?
let BARCODE:String
let THE_DATE:String
let TIME:String
}
Since you JSON has a root element ITEMS, you need to decode using this struct
struct BaseItems: Codable {
let ITEMS: [ITEM] // Actual array of items are within this JSON element
}
Usage:
do {
let decoded = try JSONDecoder().decode(BaseItems.self, from: data)
print(decoded.ITEMS)
} catch {
print(error)
}