Swift JSONDecoder error - Expected to decode Dictionary<String, Any> but found an array instead - arrays

Question

I'm new to Swift 5.3 and having trouble retrieving my nested JSON data.
My JSON data result looks like this:
{
"sites":[
{
"site_no":"16103000",
"station_nm":"Hanalei River nr Hanalei, Kauai, HI",
"dec_lat_va":22.1796,
"dec_long_va":-159.466,
"huc_cd":"20070000",
"tz_cd":"HST",
"flow":92.8,
"flow_unit":"cfs",
"flow_dt":"2020-08-18 07:10:00",
"stage":1.47,
"stage_unit":"ft",
"stage_dt":"2020-08-18 07:10:00",
"class":0,
"percentile":31.9,
"percent_median":"86.73",
"percent_mean":"50.77",
"url":"https:\/\/waterdata.usgs.gov\/hi\/nwis\/uv?site_no=16103000"
}
]
}
My structs look like this:
struct APIResponse: Codable {
let sites: APIResponseSites
}
struct APIResponseSites: Codable {
let station_nm: String
let stage: Float
}
And my Decode SWIFT looks like this:
let task = URLSession.shared.dataTask(with: url, completionHandler: {
data, _, error in
guard let data = data, error == nil else {
return
}
var result: APIResponse?
do {
result = try JSONDecoder().decode(APIResponse.self, from: data)
}
catch {
print("Failed to decode with error: \(error)")
}
guard let final = result else {
return
}
print(final.sites.station_nm)
print(final.sites.stage)
})
And of course, I get an error that states:
Failed to decode with error:
typeMismatch(Swift.Dictionary<Swift.String, Any>,
Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue:
"sites", intValue: nil)], debugDescription: "Expected to decode
Dictionary<String, Any> but found an array instead.", underlyingError:
nil))
I know it has to do with 'sites' returning an array (a single one) but I don't know how to fix it. Any help would be greatly appreciated.

Answer 1

The error message it is pretty clear you need to parse an array of objects instead of a single object.
Just change your root declaration property from
let sites: APIResponseSites
to
let sites: [APIResponseSites]

Answer 2

**1.** First "sites" is an array so replace
let sites: APIResponseSites
with
let sites: [APIResponseSites]()
**2.** As sites is a array collection, please print value like given below:
print(final.sites.first?.station_nm ?? "")
print(final.sites.first?.stage ?? 0.0)
Final code is here:
struct APIResponse: Codable {
let sites: [APIResponseSites]()
}
struct APIResponseSites: Codable {
let station_nm: String
let stage: Float
}
let task = URLSession.shared.dataTask(with: url, completionHandler: {
data, _, error in
guard let data = data, error == nil else {
return
}
var result: APIResponse?
do {
result = try JSONDecoder().decode(APIResponse.self, from: data)
}
catch {
print("Failed to decode with error: \(error)")
}
guard let final = result else {
return
}
print(final.sites.first?.station_nm ?? "")
print(final.sites.first?.stage ?? 0.0)
})