parsing YouTube json with JSONSerialization - json

Question

I have trouble parsing json data from YouTube api with JSONSerialization. when I try to fetch I return error. this is my code
this is json data I want to parse, I want to get video id, url, title, and desctiption
{
"kind": "youtube#searchListResponse",
"etag": "\"j6xRRd8dTPVVptg711_CSPADRfg/mBDPbwkuU2lLUxWHYPI1X54CUwQ\"",
"nextPageToken": "CAUQAA",
"regionCode": "ID",
"pageInfo": {
"totalResults": 3552,
"resultsPerPage": 5
},
"items": [
{
"kind": "youtube#searchResult",
"etag": "\"j6xRRd8dTPVVptg711_CSPADRfg/73cXngXOrGm_Bt7McNY945A6koc\"",
"id": {
"kind": "youtube#video",
"videoId": "-0ZZzOuuV3c"
},
"snippet": {
"publishedAt": "2018-09-20T08:00:01.000Z",
"channelId": "UCjHoMXZXAIx_QHgk9qsAJ-Q",
"title": "HADIST-HADIST PALSU TAPI POPULER - Ustadz Adi Hidayat LC MA",
"description": "\"Kebersihan sebagian dari iman\". Sering dogn mendengar ucapan ini. Sebagian orang mengatakan ini hadist dari Rasulullah. Tapi taukah kamu, bahwa ini ...",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/-0ZZzOuuV3c/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/-0ZZzOuuV3c/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/-0ZZzOuuV3c/hqdefault.jpg",
"width": 480,
"height": 360
}
},
"channelTitle": "Audio Dakwah",
"liveBroadcastContent": "none"
}
}
This is my code to parse json I create it in youtubeAPI struct, when I try to run it invalidJSONData
static func videos(fromJSON data: Data) -> VideoResults {
do {
let jsonObject = try JSONSerialization.jsonObject(with: data, options: [])
guard
let jsonDictionary = jsonObject as? [AnyHashable: Any],
let itemsArray = jsonDictionary["items"] as? [[String: Any]]
else {
return .failure(YoutubeError.invalidJSONData)
}
var finalItems = [Video]()
for itemJSON in itemsArray {
if let item = video(fromJSON: itemJSON) {
finalItems.append(item)
}
}
if finalItems.isEmpty && !itemsArray.isEmpty {
return .failure(YoutubeError.invalidJSONData)
}
return .success(finalItems)
} catch let error {
return .failure(error)
}
}
private static func video(fromJSON json: [String: Any]) ->Video? {
guard
let videoID = json["videoID"] as? String,
let title = json["title"] as? String,
let description = json["description"] as? String,
let stringURL = json["url"] as? String,
let url = URL(string: stringURL)
else {
return nil
}
return Video(videoID: videoID, title: title, description: description, url: url)
}

Answer 1

with the question I have post. finally I have the answer for my problem. hopefully this will help other developer who want to parse json with JSONSerialization, with such a complex data like YouTube api or other api. so this is my answer.
Since items is an array and inside item have another nested data such as snippet, so I need to iterate snippet to get the data. This is the code.
do {
let jsonObject = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any]
var finalItems = [Video]()
if let items = jsonObject?["items"] as? Array<Dictionary<String, Any>> {
for item in items {
if
let id = item["id"] as? [String: String],
let snippet = item["snippet"] as? [String: Any] {
if
let videoID = id["videoId"],
let description = snippet["description"] as? String,
let title = snippet["title"] as? String,
let thumbnails = snippet["thumbnails"] as? [String: Any],
let medium = thumbnails["medium"] as? [String: Any],
let urlString = medium["url"] as? String,
let url = URL(string: urlString) {
finalItems.append(Video(videoID: videoID, title: title, description: description, url: url))
}
}
}
}
print(finalItems.count)
if finalItems.isEmpty {
return .failure(YoutubeError.invalidJSONData)
}
return .success(finalItems)
} catch let error {
return .failure(error)
}
And the the next step is to clean up the code for parsing that iterate the item, and put it in extension in Video Model, I was found a good article from apple developer website to clean up the code so the code not bloated in my videos function. if you are curious check out this link https://developer.apple.com/swift/blog/?id=37. so the extension for video model is like this.
extension Video {
init(dict: [String: Any]) throws {
guard
let id = dict["id"] as? [String: String],
let videoID = id["videoId"]
else {
throw SerializationError.missing("id")
}
guard
let snippet = dict["snippet"] as? [String: Any],
let description = snippet["description"] as? String,
let title = snippet["title"] as? String,
let thumbnails = snippet["thumbnails"] as? [String: Any],
let medium = thumbnails["medium"] as? [String: Any],
let urlString = medium["url"] as? String,
let url = URL(string: urlString) else { throw SerializationError.missing("snippet") }
self.videoID = videoID
self.title = title
self.description = description
self.url = url
}
}
and then update the videos function, and add do catch block when you try to append since the extension have potential error to parse json data. this is the update method
static func videos(fromJSON data: Data) -> VideoResults {
do {
let jsonObject = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any]
var finalItems = [Video]()
if let items = jsonObject?["items"] as? Array<Dictionary<String, Any>> {
for item in items {
do {
try finalItems.append(Video(dict: item))
} catch let error {
print("Failed to append video: \(error)")
}
}
}
print(finalItems.count)
if finalItems.isEmpty {
return .failure(YoutubeError.invalidJSONData)
}
return .success(finalItems)
} catch let error {
return .failure(error)
}
}
and voila the code is safe now, why I not use JSONDecoder? since a lot of people recommended to use JSONDecoder. the reason is, this is my personal reason by the way other might not agree with me. I know how to use JSONDecoder but the thing is i don't want to create a lot struct to decode the json data, since with this JSONSerialization doesn't have to create struct it help me reduce a file and step up my learning curve. and hey even a library like Alamofire have a choice to parse using JSONSerialization. it's up to you now if you want to use JSONDecoder or JSONSerialization I hope this help :).