diff --git a/example/ios/Flutter/AppFrameworkInfo.plist b/example/ios/Flutter/AppFrameworkInfo.plist
index 6b4c0f7..f2872cf 100644
--- a/example/ios/Flutter/AppFrameworkInfo.plist
+++ b/example/ios/Flutter/AppFrameworkInfo.plist
@@ -21,6 +21,6 @@
   <key>CFBundleVersion</key>
   <string>1.0</string>
   <key>MinimumOSVersion</key>
-  <string>8.0</string>
+  <string>9.0</string>
 </dict>
 </plist>
diff --git a/example/ios/Runner.xcodeproj/project.pbxproj b/example/ios/Runner.xcodeproj/project.pbxproj
index 7da176b..3c7a119 100644
--- a/example/ios/Runner.xcodeproj/project.pbxproj
+++ b/example/ios/Runner.xcodeproj/project.pbxproj
@@ -349,7 +349,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
@@ -431,7 +431,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -480,7 +480,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
diff --git a/lib/src/expandable_section_container.dart b/lib/src/expandable_section_container.dart
index 40448a2..d0c25e3 100644
--- a/lib/src/expandable_section_container.dart
+++ b/lib/src/expandable_section_container.dart
@@ -167,8 +167,10 @@ class RenderExpandableSectionContainer extends RenderBox
 
     //when collapse last section, Sliver list not callback correct offset, so layout again.
     if (_renderSliver.sizeChanged) {
-      WidgetsBinding.instance!.addPostFrameCallback((timeStamp) {
-        markNeedsLayout();
+      WidgetsBinding.instance?.addPostFrameCallback((timeStamp) {
+        if(attached) {
+          markNeedsLayout();
+        }
       });
     }
     if (_scrollable == value) {