CODEWITHSUNDEEP
swiftgenericstypes
l30c0d35
l30c0d35

Reputation: 807

What is this function parameter for?

func load<T: Decodable>(_ filename: String, as type: T.Type = T.self) -> T {
    let data: Data

    guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
        else {
            fatalError("Couldn't find \(filename) in main bundle.")
    }

    do {
        data = try Data(contentsOf: file)
    } catch {
        fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
    }

    do {
        let decoder = JSONDecoder()
        return try decoder.decode(T.self, from: data)
    } catch {
        fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
    }
}

load("jsonFilePath")

The function extracts the data form a JSON. What is that 'parameter' type: T.Type = T.self for? If I remove this parameter the code still works. So what do I need it for?

Upvotes: 1

Views: 612

Answers (1)

Kamran
Kamran

Reputation: 15238

This parameter is just a helper to use three kind of declarations as below,

1) let model: Model = self.load("Countries")
2) let model = self.load("Countries", as: Model.self)
3) let model = self.load("Countries") as Model

You can remove it from the method signature if you want to use the first kind of declaration.

Upvotes: 5

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