An experimental share extension to send files and too much refactoring

closes #4

NearbyShare/Data+Extensions.swift

@@ -0,0 +1,47 @@
+//
+//  Data+URLSafeBase64.swift
+//  NearDrop
+//
+//  Created by Grishka on 08.04.2023.
+//
+
+import Foundation
+import CoreFoundation
+
+extension Data{
+	func urlSafeBase64EncodedString() -> String {
+		return String(base64EncodedString().replacingOccurrences(of: "=", with: "").map {
+			if $0=="/"{
+				return "_"
+			} else if $0=="+" {
+				return "-"
+			} else {
+				return $0
+			}
+		})
+	}
+	
+	static func randomData(length: Int) -> Data{
+		var data=Data(count: length)
+		data.withUnsafeMutableBytes {
+			guard 0 == SecRandomCopyBytes(kSecRandomDefault, length, $0.baseAddress!) else { fatalError() }
+		}
+		return data
+	}
+	
+	static func dataFromUrlSafeBase64(_ str:String)->Data?{
+		var regularB64=String(str.map{
+			if $0=="_"{
+				return "/"
+			}else if $0=="-"{
+				return "+"
+			}else{
+				return $0
+			}
+		})
+		while (regularB64.count%4) != 0{
+			regularB64=regularB64+"="
+		}
+		return Data(base64Encoded: regularB64, options: .ignoreUnknownCharacters)
+	}
+}