fix(ios): support excluding privacy sensitive API usage

Closes #73

Author: alpha0010

README.md

@@ -13,6 +13,15 @@ npm install react-native-file-access
 cd ios && pod install
 ```
 
+Apple restricts usage of certain privacy sensitive API calls. If you do not
+use disk space measurements or file timestamps, define the following variable
+in your Podfile to exclude restricted API calls.
+[More details.](https://github.com/alpha0010/react-native-file-access/issues/73)
+
+```ruby
+$RNFANoPrivacyAPI = true
+```
+
 If the app does not use autolinking, continue to the [manual install instructions](https://github.com/alpha0010/react-native-file-access/wiki/Manual-Installation) in the wiki.
 
 ### Compatibility

ReactNativeFileAccess.podspec

@@ -19,6 +19,13 @@ Pod::Spec.new do |s|
   s.dependency "React-Core"
   s.dependency "ZIPFoundation", "0.9.11"
 
+  if defined?($RNFANoPrivacyAPI)
+    Pod::UI.puts "#{s.name}: Removing privacy sensitive API calls"
+    s.pod_target_xcconfig = {
+      "OTHER_SWIFT_FLAGS" => "-DNO_PRIVACY_API"
+    }
+  end
+
   # Don't install the dependencies when we run `pod install` in the old architecture.
   if ENV['RCT_NEW_ARCH_ENABLED'] == '1' then
     s.compiler_flags = folly_compiler_flags + " -DRCT_NEW_ARCH_ENABLED=1"

ios/FileAccess.swift

@@ -126,6 +126,9 @@ public class FileAccess : NSObject {
     @objc(df:withRejecter:)
     public func df(resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
         DispatchQueue.global().async {
+#if NO_PRIVACY_API
+            reject("ERR", "Filesystem stat API disabled via compile time flag.", nil)
+#else
             do {
                 let stat = try FileManager.default.attributesOfFileSystem(
                     forPath: NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
@@ -138,6 +141,7 @@ public class FileAccess : NSObject {
             } catch {
                 reject("ERR", "Failed to stat filesystem. \(error.localizedDescription)", error)
             }
+#endif
         }
     }
 
@@ -350,9 +354,14 @@ public class FileAccess : NSObject {
     private func statFile(path: String) throws -> [String : Any?] {
         let pathUrl = URL(fileURLWithPath: path.path())
         let attrs = try FileManager.default.attributesOfItem(atPath: path.path())
+#if NO_PRIVACY_API
+        let lastModified = 0
+#else
+        let lastModified = 1000 * (attrs[.modificationDate] as! NSDate).timeIntervalSince1970
+#endif
         return [
             "filename": pathUrl.lastPathComponent,
-            "lastModified": 1000 * (attrs[.modificationDate] as! NSDate).timeIntervalSince1970,
+            "lastModified": lastModified,
             "path": pathUrl.path,
             "size": attrs[.size],
             "type": self.checkIfIsDirectory(path: path).isDirectory ? "directory" : "file"