Example
enum ReadResult{
case Successful
case Failed
case Pending
}
struct OutpuData {
var data = Data()
var result: ReadResult
var error: Error?
}
func readData(from url: String, completion: @escaping (OutpuData) -> Void) {
var _data = OutpuData(data: Data(), result: .Pending, error: nil)
DispatchQueue.global().async {
let url=URL(string: url)
do {
let rawData = try Data(contentsOf: url!)
_data.result = .Successful
_data.data = rawData
completion(_data)
}
catch let error {
_data.result = .Failed
_data.error = error
completion(_data)
}
}
}
readData(from: "https://raw.githubusercontent.com/trev/bearcal/master/sample-data-large.json") { (output) in
switch output.result {
case .Successful:
break
case .Failed:
break
case .Pending:
break
}
}
