Is there a way to pretty print Swift dictionaries to the console?

Question

NSDictionary *dictionary = @{@\"A\" : @\"alfa\",
                             @\"B\" : @\"bravo\",
                             @\"C\" : @\"charlie\",
                       


        

Answer 1

The methodology of converting the Swift Dictionary to json and back is the neatest. I use Facebook's chisel which has a pjson command to print a Swift dictionary. Eg:

(lldb) pjson dict as NSDictionary

This should pretty-print the dictionary. This is a much cleaner way to do what has already been suggested. P.S. For now, you'll have to cast dict as NSDictionary because Objective-C runtime doesn't understand Swift dictionaries. I have already raised a PR on chisel to get rid of that restriction.

UPDATE: My PR got accepted. Now you can use psjson command instead of pjson mentioned above.

Answer 2

When debugging, output the struct that conform Codable Protocol to the console
use json format.

extension Encodable {
    var jsonData: Data? {
        let encoder = JSONEncoder()
        encoder.outputFormatting = .prettyPrinted
        return try? encoder.encode(self)
    }
}

extension Encodable where Self: CustomDebugStringConvertible {
    var debugDescription: String {
         if let data = self.jsonData,
             let string = String(data: data, encoding: .utf8) {
             return string
         }
         return "can not convert to json string"
     }
}

strcut conform CustomDebugStringConvertible

struct Test: Codable, CustomDebugStringConvertible {
    let a: String
    let b: Int
}

let t = Test(a: "test string", b: 30)

debug print struct

(lldb) p print(t)
{
  "a" : "test string",
  "b" : 30
}

Answer 3

po solution

For those of you want to see Dictionary as JSON with out escape sequence in console, here is a simple way to do that

(lldb)p print(String(data: try! JSONSerialization.data(withJSONObject: object, options: .prettyPrinted), encoding: .utf8 )!)

Update

Check this answer too Answer

Answer 4

Just another way using Functional Programming

dictionary.forEach { print("\($0): \($1)") }

Output

B: bravo
A: alfa
F: foxtrot
C: charlie
D: delta
E: echo

Answer 5

For debug purpose only I would convert the Array or Dictionary to a pretty printed json:

public extension Collection {

    /// Convert self to JSON String.
    /// Returns: the pretty printed JSON string or an empty string if any error occur.
    func json() -> String {
        do {
            let jsonData = try JSONSerialization.data(withJSONObject: self, options: [.prettyPrinted])
            return String(data: jsonData, encoding: .utf8) ?? "{}"
        } catch {
            print("json serialization error: \(error)")
            return "{}"
        }
    }
}

Then:

print("\nHTTP request: \(URL)\nParams: \(params.json())\n")

Result on console:

HTTP request: https://example.com/get-data
Params: {
  "lon" : 10.8663676,
  "radius" : 111131.8046875,
  "lat" : 23.8063882,
  "index_start" : 0,
  "uid" : 1
}

Answer 6

You can just use a for loop and print each iteration

for (key,value) in dictionary { 
    print("\(key) = \(value)")
}

Application in extension:

extension Dictionary where Key: CustomDebugStringConvertible, Value:CustomDebugStringConvertible {

    var prettyprint : String {
        for (key,value) in self {
            print("\(key) = \(value)")
        }

        return self.description
    }
}

Alternate application:

extension Dictionary where Key: CustomDebugStringConvertible, Value:CustomDebugStringConvertible {

    func prettyPrint(){
        for (key,value) in self {
            print("\(key) = \(value)")
        }
    }
}

Usage:

dictionary.prettyprint //var prettyprint
dictionary.prettyPrint //func prettyPrint

Output (Tested in Xcode 8 beta 2 Playground):

A = alfa
B = bravo
C = charlie
D = delta
E = echo
F = foxtrot