Various improvements

submodules/TelegramCore/Sources/Utils/JSON.swift

@@ -50,6 +50,18 @@ extension JSON {
             return nil
         }
     }
+    
+    public init?(dictionary: [String: Any]) {
+        var values: [String: JSON] = [:]
+        for (key, value) in dictionary {
+            if let v = JSON(value) {
+                values[key] = v
+            } else {
+                return nil
+            }
+        }
+        self = .dictionary(values)
+    }
 }
 
 extension JSON: Collection {
@@ -125,7 +137,7 @@ extension JSON {
         get {
             switch self {
                 case .null:
-                    return 0
+                    return NSNull()
                 case let .number(value):
                     return value
                 case let .string(value):
@@ -172,6 +184,18 @@ extension JSON {
     }
 }
 
+extension JSON {
+    public var string: String? {
+        guard let jsonData = try? JSONSerialization.data(withJSONObject: self.value) else {
+            return nil
+        }
+        guard let jsonDataString = String(data: jsonData, encoding: .utf8) else {
+            return nil
+        }
+        return jsonDataString
+    }
+}
+
 extension JSON: ExpressibleByDictionaryLiteral {
     public init(dictionaryLiteral elements: (String, Any)...) {
         self = .dictionary(elements.reduce([String: JSON]()) { (dictionary, element) in
@@ -195,6 +219,12 @@ private protocol JSONValue {
     var jsonValue: JSON { get }
 }
 
+extension NSNull: JSONElement, JSONValue {
+    var jsonValue: JSON {
+        return .null
+    }
+}
+
 extension Int: JSONElement, JSONValue {
     var jsonValue: JSON {
         return .number(Double(self))