Implementation of NSMutableDictionary.init(contentsOfFile:)

Author: saiHemak

Foundation/NSDictionary.swift

@@ -563,8 +563,20 @@ open class NSMutableDictionary : NSDictionary {
         super.init(objects: objects, forKeys: keys, count: cnt)
     }
 
-    public convenience init?(contentsOfFile path: String) { NSUnimplemented() }
-    public convenience init?(contentsOfURL url: URL) { NSUnimplemented() }
+    public convenience init?(contentsOfFile path: String) {
+        self.init(contentsOfURL: URL(fileURLWithPath: path))
+    }
+    
+    public convenience init?(contentsOfURL url: URL) {
+        do {
+            guard let plistDoc = try? Data(contentsOf: url) else { return nil }
+            let plistDict = try PropertyListSerialization.propertyList(from: plistDoc, options: [], format: nil) as? Dictionary<AnyHashable,Any>
+            guard let plistDictionary = plistDict else { return nil }
+            self.init(dictionary: plistDictionary)
+        } catch {
+            return nil
+        }
+    }
 }
 
 extension NSMutableDictionary {

TestFoundation/TestNSDictionary.swift

@@ -31,6 +31,7 @@ class TestNSDictionary : XCTestCase {
             ("test_copying", test_copying),
             ("test_mutableCopying", test_mutableCopying),
             ("test_writeToFile", test_writeToFile),
+            ("test_initWithContentsOfFile", test_initWithContentsOfFile),
         ]
     }
 
@@ -186,6 +187,23 @@ class TestNSDictionary : XCTestCase {
             XCTFail("Temporary file creation failed")
         }
     }
+    
+    func test_initWithContentsOfFile() {
+        let testFilePath = createTestFile("TestFileOut.txt", _contents: Data(capacity: 256))
+        if let _ = testFilePath {
+            let d1: NSDictionary = ["Hello":["world":"again"]]
+            let isWritten = d1.write(toFile: testFilePath!, atomically: true)
+            if(isWritten) {
+                let dict = NSMutableDictionary.init(contentsOfFile: testFilePath!)
+                XCTAssert(dict == d1)
+            } else {
+                XCTFail("Write to file failed")
+            }
+            removeTestFile(testFilePath!)
+        } else {
+            XCTFail("Temporary file creation failed")
+        }
+    }
 
     private func createTestFile(_ path: String, _contents: Data) -> String? {
         let tempDir = "/tmp/TestFoundation_Playground_" + NSUUID().uuidString + "/"