Parsing json string crashes - ios

Question

I'm trying to parse a json string:
if let jsonStr = asd.value(forKey: "orderData") as? String {
print(jsonStr)
let data = jsonStr.data(using: String.Encoding.utf8, allowLossyConversion: false)!
do {
let json = try JSONSerialization.jsonObject(with: data, options: []) as! [String: AnyObject] // CRASHES HERE
if let names = json["product_name"] as? [String] {
print(names)
}
} catch let error as NSError {
print("Failed to load: \(error.localizedDescription)")
}
}
But at the line let json = try JSONSeri... it crashes saying Could not cast value of type '__NSArrayI' to 'NSDictionary'.
Also tried changing this as! [String: AnyObject] to as! [[String: AnyObject]]. But it still doesn't work.
This is my json string structure:
[
{
"product_id" : "1",
"category_json" : {
"category_id" : "1",
"category_name" : "nvm"
},
"selling_price" : "200",
"product_name" : "nvm",
},
{
"product_id" : "2",
"category_json" : {
"category_id" : "2",
"category_name" : "cas"
},
"selling_price" : "800",
"product_name" : "cas",
}
]

Answer 1

You should not be force casting with ! unless you are 100% sure that it will succeed.
I would suggest you use the following:
let jsonArray = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [[String: Any]]
This will return you a list of products. If you want a list of the product names than you need to iterate over it and extract the product name of each item. You can do this like so:
let names = jsonArray.map({ $0["product_name"] as? String })

Answer 2

As already mentioned the object is an array, you have to use a for loop to get all items
...
let data = Data(jsonStr.utf8)
do {
if let json = try JSONSerialization.jsonObject(with: data) as? [[String: Any]] {
for item in json {
if let name = item["product_name"] as? String {
print(name)
}
}
}
} catch {
print("Failed to load: \(error.localizedDescription)")
}