How can I update labels and UIImage placeholder from local JSON? - json

Question

So I have a JSON file that I need to parse and update labels and image. In my storyboard I have 4 labels (image of an animal, region, it's weight and length) and uiimage where I need to put it's picture.
I need to update labels and image by parsing JSON.
This is how far I was able to get to...
My JSON look like this:
"data":[
{
"name":"Lion",
"thumbnail":"https://kopelion.org/wp-content/uploads/2016/10/Kimani.jpg",
"region":"Africa",
"stats":{
"max_weight":180,
"length":250
}
}
]
I tried to get into this by writing:
override func viewDidLoad() {
super.viewDidLoad()
guard let path = Bundle.main.path(forResource: "data", ofType: "json") else { return }
let url = URL(fileURLWithPath: path)
do {
let data = try Data(contentsOf: url)
let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers)
print(json)
guard let array = json as? [Any] else { return }
for animal in array {
guard let animalDict = animal as? [String: Any] else { return }
guard let animalName = animalDict["name"] as? String else { return }
guard let animalRegion = animalDict["region"] as? String else { return }
guard let animalStats = animalDict["stats"] as? String else { return }
print(animalName)
print(animalRegion)
print(animalStats)
}
} catch {
print(error)
}
}

Answer 1

First thing first, most of the times the main culprit is json file itself, as in your case.
You need to fix the json code first, by adding "{" at the top and "}" at the bottom of your json file's code.
This will make it valid json
And then do the following
Replace your code lines:
// 1
guard let array = json as? [Any] else { return }
// 2
guard let animalStats = animalDict["stats"] as? String else { return }
with this:
// 1
guard let dictionary = json as? [String:[Any]] else { return }
guard let array = dictionary["data"] else { return }
//2
guard let animalRegion = animalDict["region"] as? String else { return }
Quik tip : 1. Check your json using online tools like https://codebeautify.org/jsonviewer
Try to use JSONDecoder and JSONEncoder instead of JSONSerialization

Answer 2

You'll need to have properties in your class for the storyboard items you want to set. e.g.,:
#IBOutlet weak var name: UILabel! // outside functions but inside class, and hooked up in Storyboard
// inside viewDidLoad
name.text = animalDict["name"] as? String
I wouldn't bother with the intermediate variables unless you really need them.

Answer 3

As you are responsible for the JSON delete the enclosing dictionary data, it's not needed.
[{
"name":"Lion",
"thumbnail":"https://kopelion.org/wp-content/uploads/2016/10/Kimani.jpg",
"region":"Africa",
"stats":{
"max_weight":180,
"length":250
}
}]
Create two structs
struct Animal: Decodable {
let name: String
let thumbnail: URL
let region: String
let stats: Stats
}
struct Stats: Decodable {
let maxWeight, length: Int
}
In the view controller declare a data source array
var animals = [Animal]()
In viewDidLoad parse the data with JSONDecoder and assign the result to the data source array
override func viewDidLoad() {
super.viewDidLoad()
let url = Bundle.main.url(forResource: "data", withExtension: "json")!
let data = try! Data(contentsOf: url)
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
self.animals = try! decoder.decode([Animal].self, from: data)
}
All guards and trys are actually not needed. The file must exist at compile time and cannot be modified at runtime so the code must not crash.
You can get the animal properties with
let animal = animals[0]
let name = animal.name
let weight = animal.stats.weight
print(name, weight)
Assuming there are more animals in the JSON use a loop
for animal in animals {
let name = animal.name
let weight = animal.stats.weight
print(name, weight)
}
How to update the labels is unclear because there is no significant information about the design in your question.
To get the image load it asynchronously with URLSession