             self?.indicator.stopAnimating()
             
             // 前回読み込んだページ数を取得する.
-            let currentIndex = UserDefaults.standard.integer(forKey: UDKey.CurrentPage)
+            guard let currentIndex = self?.getCurrentPage() else {return}
             self?.leavesView.reloadData()
             self?.leavesView.currentPageIndex = currentIndex
             

        preBtn.isEnabled = chapterNumber != 0
        nextBtn.isEnabled = chapterNumber != model.chapterInfos.count - 1
    }

    // #program mark  delegate.
    override func leavesView(leavesView: LeavesView, willTurnToPageAtIndex pageIndex: Int) {

    }
    
    @IBAction func toNextChapter() {
        let currentIndex = self.getCurrentPage()
        var nextInfo : ChapterInfo!
        
        for i in (0..<model.chapterInfos.count).reversed() {
