fix epub reader playback and trial navigation

Sources/RDEpubReaderView/EPUBUI/RDEPUBReaderController.swift

@@ -149,6 +149,10 @@ public final class RDEPUBReaderController: UIViewController {
     /// 试读墙视图缓存（经 delegate 获取一次后复用；见 RDEPUBReaderController+Trial）
     var cachedTrialWallView: UIView?
 
+    /// 阅读器进入前宿主导航栏的真实状态。详情页使用自定义导航栏时系统栏原本
+    /// 就是隐藏的，退出阅读器必须恢复该状态，不能无条件显示系统导航栏。
+    private var navigationBarHiddenBeforeReader: Bool?
+
     private(set) var isSearchBarVisible = false
 
     var currentBookIdentifier: String? {
@@ -275,6 +279,9 @@ public final class RDEPUBReaderController: UIViewController {
 
     public override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
+        if navigationBarHiddenBeforeReader == nil {
+            navigationBarHiddenBeforeReader = navigationController?.isNavigationBarHidden
+        }
         navigationController?.setNavigationBarHidden(true, animated: animated)
         navigationController?.interactivePopGestureRecognizer?.delegate = self
         navigationController?.interactivePopGestureRecognizer?.isEnabled = true
@@ -282,7 +289,12 @@ public final class RDEPUBReaderController: UIViewController {
 
     public override func viewWillDisappear(_ animated: Bool) {
         super.viewWillDisappear(animated)
-        navigationController?.setNavigationBarHidden(false, animated: animated)
+        if let navigationBarHiddenBeforeReader {
+            navigationController?.setNavigationBarHidden(
+                navigationBarHiddenBeforeReader,
+                animated: animated
+            )
+        }
     }
 
     public override func viewDidAppear(_ animated: Bool) {