how to avail the catch concept in swift 2.0

Question

I just converted my code to Swift 2.0 and it converted the code beautifully.

Just one thing I am not able to understand that how to use the try-catch in my codes.

I am posting the data and getting the JSON formatted

if anything goes wrong in network then it throws error and app crashes when JSON serialisation is done. How to prevent this, my code snap is below.

do {
            json =  try! NSJSONSerialization.JSONObjectWithData(data!, options: .MutableLeaves) as? NSDictionary
        }
        catch {
            // report error
        }

It crashed in the line

 json =  try! NSJSONSerialization.JSONObjectWithData(data!, options: .MutableLeaves) as? NSDictionary

How to use catch so that it does not crash here and shows error!!!

just try not try! , try! mean crash if error ,try mean if error go to catch . you have to declare an error variable as NSError for catching the error : catch let error as NSError — kholl, Jan 07 '16 at 10:30
Possible duplicate of [Error-Handling in Swift-Language](http://stackoverflow.com/questions/24010569/error-handling-in-swift-language) — Cristik, Jan 07 '16 at 13:41

score 1 · Answer 1 · answered Jan 07 '16 at 10:32

1

I'm using it in my project like

do{
        if let result = try NSJSONSerialization.JSONObjectWithData(resultData, options: []) as? NSMutableDictionary{
        }
    }
    catch let error as NSError{
        print("Error : \(error)")
    }

answered Jan 07 '16 at 10:32

Ankita Shah

2,178
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score 0 · Answer 2 · answered Jan 07 '16 at 10:37

0

use this syntax, and remove the "!" in the try

do {
            json =  try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableLeaves) as? NSDictionary
        }
        catch _ {
            // report error
            print("Exception")
        }

answered Jan 07 '16 at 10:37

Diego

2,395
2
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27

1

It would be better to print the actual error message rather than "Exception". :) – Eric Aya Jan 07 '16 at 11:28
Yes, it's true. my only I wanted to be an example. – Diego Jan 07 '16 at 12:06

score 0 · Answer 3 · answered Jan 07 '16 at 10:51

0

like diego said but the catch do like this to see what is the error you get in case you get one for debugging

catch let error as NSError{
    print("Error : \(error)")
    //or NSLog()
    NSLog("Error = %@",error)
}

answered Jan 07 '16 at 10:51

Igor Sokolovsky

87
9

how to avail the catch concept in swift 2.0

3 Answers3