Invalid conversion from throwing function of type (_,_,_) throws -> Void to non-throwing function type (NSData?, NSURLResponse?, NSError?) -> Void
You need to implement Do Try Catch error handling as follow:
import UIKitimport PlaygroundSupportPlaygroundPage.current.needsIndefiniteExecution = trueextension URL { func asyncDownload(completion: @escaping (_ data: Data?, _ response: URLResponse?, _ error: Error?) -> ()) { URLSession.shared .dataTask(with: self, completionHandler: completion) .resume() }}
let jsonURL = URL(string: "https://api.whitehouse.gov/v1/petitions.json?limit=100")!let start = Date()jsonURL.asyncDownload { data, response, error in print("Download ended:", Date().description(with: .current)) print("Elapsed Time:", Date().timeIntervalSince(start), terminator: " seconds\n") print("Data size:", data?.count ?? "nil", terminator: " bytes\n\n") guard let data = data else { print("URLSession dataTask error:", error ?? "nil") return } do { let jsonObject = try JSONSerialization.jsonObject(with: data) if let dictionary = jsonObject as? [String: Any], let results = dictionary["results"] as? [[String: Any]] { DispatchQueue.main.async { results.forEach { print($0["body"] ?? "", terminator: "\n\n") } // self.tableData = results // self.Indextableview.reloadData() } } } catch { print("JSONSerialization error:", error) }}print("\nDownload started:", start.description(with: .current))
As Leo suggested, your problem is that you're using try
, but not within the do
-try
-catch
construct, which means that it infers that the closure is defined to throwing the error, but since it is not defined as such, you get that error.
So, add do
-try
-catch
:
func getjson() { let urlPath = "https://api.whitehouse.gov/v1/petitions.json?limit=100" let url = URL(string: urlPath)! let session = URLSession.shared let task = session.dataTask(with: url) { data, response, error in print("Task completed") guard let data = data, error == nil else { print(error?.localizedDescription) return } do { if let jsonResult = try JSONSerialization.jsonObject(with: data) as? [String: Any] { if let results = jsonResult["results"] as? [Any] { DispatchQueue.main.async { self.tableData = results self.indexTableView.reloadData() } } } } catch let parseError { print("JSON Error \(parseError.localizedDescription)") } } task.resume()}
In Swift 2, replace all NSError
with ErrorType
Try this.
class func fetchWeatherForLocation(locationCode: String = "", shouldShowHUD: Bool = false, completionHandler: (data: NSDictionary?, error: ErrorType?) -> ()) { let url = NSURL(string: "myurl") let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in if let dataWithKey = data { do { let jsonForDataWithTemprature = try NSJSONSerialization.JSONObjectWithData(dataWithKey, options:NSJSONReadingOptions.MutableContainers) guard let arrayForDataWithKey :NSArray = jsonForDataWithTemprature as? NSArray else { print("Not a Dictionary") return } let dictionaryWithTemprature = arrayForDataWithKey.firstObject as! NSDictionary completionHandler(data: dictionaryWithTemprature, error: nil) } catch let JSONError as ErrorType { print("\(JSONError)") } } } task.resume()}