fatal error: unexpectedly found nil while unwrapping an Optional value in Swift when tried to parse JSON

Question

I\'ve tried to build up a document-based Cocoa app and when I tried to parse JSON in readFromData: ofType: error: method, I got an error: fatal error: unexpec

Answer 1

• In this case outError is supplied as an argument so you should use it (I overlooked that).
• Looks like this function's purpose is to check whether data is valid JSON.

Then your funciton should be:

override func readFromData(data: NSData?, ofType typeName: String?, error outError: NSErrorPointer) -> Bool {
    if let loadedDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.AllowFragments, error: outError) as? NSDictionary {
       return true
    } else {
       return false
    }
}

Now this function:

• write error to where the caller specified in ourError should error occur
• return wheter the data is valid JSON as NSDictionary

FYI I happened to write a JSON handler, too.

• https://github.com/dankogai/swift-json/

Which includes NSJSONSerialization.JSONObjectWithData.