Errors thrown from here are not handled

Question

I've got this problem trying to parse a JSON on my iOS app:

Relevant code:

let jsonData:NSDictionary = try JSONSerialization.jsonObject(with: urlData! as Data, options: JSONSerialization.ReadingOptions.mutableContainers ) as! NSDictionary

/* XCode error ^^^ Errors thrown from here are not handled */

Could anybody help me ?

And if you are using Swift 3, use Swift 3 types. Use `Data`, not `NSData`. Use `Error`, not `NSError`. Use Swift arrays and dictionaries, not `NSArray` and `NSDictionary`. — rmaddy, Nov 07 '16 at 16:41
And do what the error messages tells you to do. You're using `try` but it's not into a proper Do-Catch scope... — Eric Aya, Nov 07 '16 at 16:42

shallowThought · Accepted Answer · 2020-03-07T14:39:07.533

119

A possibly thrown error in let jsonData = try JSONSerialization ... is not handled.

You can ignore a possible error, and crash as penalty if an error occurs:

let jsonData = try! JSONSerialization ...

or return an Optional, so jsonData is nil in error case:

let jsonData = try? JSONSerialization ...

or you can catch and handle the thrown error:

do {
    let jsonData = try JSONSerialization ...
    //all fine with jsonData here
} catch {
    //handle error
    print(error)
}

You might want to study The Swift Language

edited Mar 07 '20 at 14:39

answered Nov 07 '16 at 16:46

shallowThought

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You deserved an up vote! I'm new to Swift! Oh man, Swift is a pain in the ass at first! <3 – Randika Vishman Jun 08 '17 at 21:11
1

Another possibility: Inside a throwing function f, you can call another throwing function g without using "try". If g throws an error, f returns immediately and throws the same error. – gnasher729 Jan 13 '20 at 22:47

Errors thrown from here are not handled

1 Answers1