feat: support read data to base 64 encoded string

Fixes #12

Author: alpha0010

README.md

@@ -86,8 +86,9 @@ type FetchResult = {
 `FileSystem.mv(source: string, target: string): Promise<void>`
 - Move a file.
 
-`FileSystem.readFile(path: string): Promise<string>`
+`FileSystem.readFile(path: string, encoding?: 'utf8' | 'base64'): Promise<string>`
 - Read the content of a file.
+  - Default encoding of returned string is utf8.
 
 ```
 FileSystem.stat(path: string): Promise<FileStat>

android/src/main/java/com/alpha0010/fs/FileAccessModule.kt

@@ -317,9 +317,13 @@ class FileAccessModule(reactContext: ReactApplicationContext) : ReactContextBase
   }
 
   @ReactMethod
-  fun readFile(path: String, promise: Promise) {
+  fun readFile(path: String, encoding: String, promise: Promise) {
     try {
-      promise.resolve(File(path).readText())
+      if (encoding == "base64") {
+        promise.resolve(Base64.encodeToString(File(path).readBytes(), Base64.DEFAULT))
+      } else {
+        promise.resolve(File(path).readText())
+      }
     } catch (e: Throwable) {
       promise.reject(e)
     }

ios/FileAccess.m

@@ -58,6 +58,7 @@ @interface RCT_EXTERN_REMAP_MODULE(RNFileAccess, FileAccess, NSObject)
                  withRejecter:(RCTPromiseRejectBlock)reject)
 
 RCT_EXTERN_METHOD(readFile:(NSString *)path
+                 withEncoding:(NSString *)encoding
                  withResolver:(RCTPromiseResolveBlock)resolve
                  withRejecter:(RCTPromiseRejectBlock)reject)
 

ios/FileAccess.swift

@@ -253,10 +253,15 @@ class FileAccess: NSObject {
         }
     }
 
-    @objc(readFile:withResolver:withRejecter:)
-    func readFile(path: String, resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
+    @objc(readFile:withEncoding:withResolver:withRejecter:)
+    func readFile(path: String, encoding: String, resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
         do {
-            try resolve(String(contentsOfFile: path))
+            if encoding == "base64" {
+                let binaryData = try Data(contentsOf: URL(fileURLWithPath: path))
+                resolve(binaryData.base64EncodedString())
+            } else {
+                try resolve(String(contentsOfFile: path))
+            }
         } catch {
             reject("ERR", "Failed to read '\(path)'.", error)
         }

src/index.ts

@@ -130,8 +130,8 @@ export const FileSystem = {
   /**
    * Read the content of a file.
    */
-  readFile(path: string) {
-    return FileAccessNative.readFile(path);
+  readFile(path: string, encoding: Encoding = 'utf8') {
+    return FileAccessNative.readFile(path, encoding);
   },
 
   /**

src/native.ts

@@ -34,7 +34,7 @@ type FileAccessType = {
   ls(path: string): Promise<string[]>;
   mkdir(path: string): Promise<void>;
   mv(source: string, target: string): Promise<void>;
-  readFile(path: string): Promise<string>;
+  readFile(path: string, encoding: Encoding): Promise<string>;
   stat(path: string): Promise<FileStat>;
   unlink(path: string): Promise<void>;
   writeFile(path: string, data: string, encoding: Encoding): Promise<void>;