CODEWITHSUNDEEP
iosjsonswiftparsinglogging
Sazzad Hissain Khan
Sazzad Hissain Khan

Reputation: 40237

Swift - JSON String printing \n instead of new line

I wonder if there is any way to print exact JSON string in pretty format while logging. I was printing a http request header fields like,

let jsonData = try JSONSerialization.data(withJSONObject: dictionary, options: .prettyPrinted)
let jsonString = String(bytes: jsonData, encoding: String.Encoding.utf8)
MyLogUtil.logVerbose(message: "\(String(describing: jsonString))")

But instead of printing expected logs like below,

{
   "user": {
       name: "Test",
       age: "30"
    }
}

Its printing something like,

{\n"user": {\nname: "Test",\n\nage: "30"\n}\n}\n

How to get rid of this issue?

EDIT: @AwaisFayyaz

func requestTest() -> Void {

        let task = URLSession.shared.dataTask(with: URL(string: "https://jsonplaceholder.typicode.com/posts")!) { (data, response, error) in

            do {

                let json = try JSONSerialization.jsonObject(with: data!, options: []) as! [String: Any]
                if let userDict = json["user"] as? NSDictionary {
                    print(userDict)
                }
            }
            catch let error as NSError {

                print("Failed to load: \(error.localizedDescription)")
            }
        }
        task.resume()
    }

Above code got crashed!

enter image description here

Upvotes: 0

Views: 3413

Answers (1)

Awais Fayyaz
Awais Fayyaz

Reputation: 2415

Suppose this is your input string that you want to print in pretty format. Then 

let str = "{\"user\":{\"name\":\"Test\",\"age\":\"30\"} }"

Then use 

let data = str.data(using: String.Encoding.utf8, allowLossyConversion: false)!

do {
  let json = try JSONSerialization.jsonObject(with: data, options: []) as! [String: AnyObject]

  if let userDict = json["user"] as? NSDictionary {
    print(userDict)
  }


} catch let error as NSError {
  print("Failed to load: \(error.localizedDescription)")
}

I have implemented the code. See the console output in the image

enter image description here

@Answer to Edit

Your code is crashing because JSON is returning An Array and you are force casting as [String: Any] (not possible). Instead cast it as NSArray

use the following code snippet in this case

func requestTest() -> Void {

let task = URLSession.shared.dataTask(with: URL(string: "https://jsonplaceholder.typicode.com/posts")!) { (data, response, error) in

  do {
    //cast it as Array
    let usersArray = try JSONSerialization.jsonObject(with: data!, options: []) as! NSArray
    for userDictAny in usersArray {
      //cast the type of userDictAny to NSDictionary
      guard let userDict = userDictAny as? NSDictionary else {
        print("Error. Count not cast as NSDictionary. Going to return")
        return
      }
      print("\n\n\(userDict)\n\n")
      //additionaly, if you want to get value of individual fields from userDict
      if let userId = userDict["userId"] as? Int64 {
        print("Value of userID \(userId)")
      }
      //in the same way get more values if you want from userDict

    }


  }
  catch let error as NSError {

    print("Failed to load: \(error.localizedDescription)")
  }
}
task.resume()
}

Note that original ordering of data will not be preserved because it is a dictionary. But you can see your output in nice format

Output Snapshot of running code output for updated code

Upvotes: 1

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