获取extension，判断第一次

keyBoard/AppDelegate.m

@@ -38,15 +38,53 @@ static BOOL KBIsKeyboardEnabled(void) {
     ViewController *vc = [[ViewController alloc] init];
     self.window.rootViewController = vc;
     
-    // Present guide if the custom keyboard is not enabled yet
+//    [[NSNotificationCenter defaultCenter] addObserver:self
+//                                             selector:@selector(applicationDidBecomeActiveNotification:)
+//                                                 name:UIApplicationDidBecomeActiveNotification
+//                                               object:nil];
+
     dispatch_async(dispatch_get_main_queue(), ^{
-        if (!KBIsKeyboardEnabled()) {
-            KBPermissionViewController *guide = [KBPermissionViewController new];
-            guide.modalPresentationStyle = UIModalPresentationFullScreen;
-            [self.window.rootViewController presentViewController:guide animated:YES completion:nil];
-        }
+        [self kb_presentPermissionIfNeeded];
     });
     return YES;
 }
+//
+//#pragma mark - Active notifications
+//
+//- (void)applicationDidBecomeActiveNotification:(NSNotification *)note
+//{
+//    [self kb_presentPermissionIfNeeded];
+//}
+
+#pragma mark - Permission presentation
+
+- (UIViewController *)kb_topMostViewController
+{
+    UIViewController *root = self.window.rootViewController;
+    if (!root) return nil;
+    UIViewController *top = root;
+    while (top.presentedViewController) {
+        top = top.presentedViewController;
+    }
+    return top;
+}
+
+- (void)kb_presentPermissionIfNeeded
+{
+    BOOL enabled = KBIsKeyboardEnabled();
+    UIViewController *top = [self kb_topMostViewController];
+    if (!top) return;
+    if ([top isKindOfClass:[KBPermissionViewController class]]) {
+        if (enabled) {
+            [top dismissViewControllerAnimated:YES completion:nil];
+        }
+        return;
+    }
+    if (!enabled) {
+        KBPermissionViewController *guide = [KBPermissionViewController new];
+        guide.modalPresentationStyle = UIModalPresentationFullScreen;
+        [top presentViewController:guide animated:YES completion:nil];
+    }
+}
 
 @end