Prevent to always unzip the ePub, performance improvement 📈

Source/EPUBCore/FREpubParser.swift

@@ -26,29 +26,44 @@ class FREpubParser: NSObject, SSZipArchiveDelegate {
      Returns an UIImage.
      */
     func parseCoverImage(epubPath: String) -> UIImage? {
-        let book = readEpub(epubPath: epubPath, removeEpub: false)
-
-        // Read the cover image
-        if let coverImage = book.coverImage {
-            return UIImage(contentsOfFile: coverImage.fullHref)
+        guard let book = readEpub(epubPath: epubPath, removeEpub: false),
+            let coverImage = book.coverImage else {
+                return nil
         }
 
-        return nil
+        return UIImage(contentsOfFile: coverImage.fullHref)
     }
 
     /**
      Unzip, delete and read an epub file.
      Returns a FRBook.
     */
 
-    func readEpub(epubPath withEpubPath: String, removeEpub: Bool = true) -> FRBook {
+    func readEpub(epubPath withEpubPath: String, removeEpub: Bool = true) -> FRBook? {
         epubPathToRemove = withEpubPath
         shouldRemoveEpub = removeEpub
 
-        // Unzip   
+        var isDir: ObjCBool = false
+        let fileManager = NSFileManager.defaultManager()
         let bookName = (withEpubPath as NSString).lastPathComponent
         bookBasePath = (kApplicationDocumentsDirectory as NSString).stringByAppendingPathComponent(bookName)
-        SSZipArchive.unzipFileAtPath(withEpubPath, toDestination: bookBasePath, delegate: self)
+
+        guard fileManager.fileExistsAtPath(withEpubPath) else {
+            print("Epub file does not exist.")
+            return nil
+        }
+
+        // Unzip if necessary
+        var needsUnzip = false
+        if fileManager.fileExistsAtPath(bookBasePath, isDirectory:&isDir) {
+            if !isDir { needsUnzip = true }
+        } else {
+            needsUnzip = true
+        }
+
+        if needsUnzip {
+            SSZipArchive.unzipFileAtPath(withEpubPath, toDestination: bookBasePath, delegate: self)
+        }
 
         // Skip from backup this folder
         addSkipBackupAttributeToItemAtURL(NSURL(fileURLWithPath: bookBasePath, isDirectory: true))
@@ -59,18 +74,6 @@ class FREpubParser: NSObject, SSZipArchiveDelegate {
         return book
     }
 
-    /**
-     Read an unziped epub file.
-     Returns a FRBook.
-    */
-    func readEpub(filePath withFilePath: String) -> FRBook {
-        bookBasePath = withFilePath
-        kBookId = (withFilePath as NSString).lastPathComponent
-        readContainer()
-        readOpf()
-        return book
-    }
-
     /**
      Read and parse container.xml file.
     */

Source/FolioReaderContainer.swift

@@ -124,17 +124,9 @@ public class FolioReaderContainer: UIViewController {
 
         dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), { () -> Void in
 
-            var isDir: ObjCBool = false
-            let fileManager = NSFileManager.defaultManager()
-
-            if fileManager.fileExistsAtPath(self.epubPath, isDirectory:&isDir) {
-                if isDir {
-                    book = FREpubParser().readEpub(filePath: self.epubPath)
-                }
-
-                book = FREpubParser().readEpub(epubPath: self.epubPath, removeEpub: self.shouldRemoveEpub)
+            if let parsedBook = FREpubParser().readEpub(epubPath: self.epubPath, removeEpub: self.shouldRemoveEpub) {
+                book = parsedBook
             } else {
-                print("Epub file does not exist.")
                 self.errorOnLoad = true
             }