Remove useless system version code (#1396)

Summary:
## Changes in this pull request

`Examples/Examples-iOS/Pods/Pods.xcodeproj/project.pbxproj`
`Examples/Examples-tvOS/Pods/Pods.xcodeproj/project.pbxproj`

this change just Xcode 11.2 generated.

This pr aim to remove useless `IGSystemVersion` file.

### Checklist

- [x] All tests pass. Demo project builds and runs.
- [ ] I added tests, an experiment, or detailed why my change isn't tested.
- [x] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
- [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
Pull Request resolved: #1396

Reviewed By: lorixx

Differential Revision: D18638299

Pulled By: iperry90

fbshipit-source-id: 0b6583f1210e5d1570dd672eed8c59901d6785f6

CHANGELOG.md

@@ -34,6 +34,8 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
 
 - Update CocoaPods integration to use the CocoaPods specs CDN [Koen Punt](https://github.com/koenpunt) (#1386)
 
+- Remove useless system version code [Kinarobin](https://github.com/kinarobin) [(#1386)](https://github.com/Instagram/IGListKit/pull/1396)
+
 ### Fixes
 
 - Fixed bug with layouts inconsistency in `updateAnimated:completion` of IGListBindingSectionController. [Qinghua Hong](https://github.com/xohozu) [(#1285)](https://github.com/Instagram/IGListKit/pull/1285)

IGListKit.xcodeproj/project.pbxproj

@@ -156,8 +156,6 @@
 		7A02CF9A2361513600B49FAE /* IGListBindingSectionController+DebugDescription.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF672361513400B49FAE /* IGListBindingSectionController+DebugDescription.h */; };
 		7A02CF9C2361513600B49FAE /* IGListCollectionViewLayoutInternal.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF682361513400B49FAE /* IGListCollectionViewLayoutInternal.h */; };
 		7A02CF9D2361513600B49FAE /* IGListCollectionViewLayoutInternal.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF682361513400B49FAE /* IGListCollectionViewLayoutInternal.h */; };
-		7A02CF9F2361513600B49FAE /* IGSystemVersion.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF692361513400B49FAE /* IGSystemVersion.h */; };
-		7A02CFA02361513600B49FAE /* IGSystemVersion.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF692361513400B49FAE /* IGSystemVersion.h */; };
 		7A02CFA22361513600B49FAE /* UIScrollView+IGListKit.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF6A2361513400B49FAE /* UIScrollView+IGListKit.h */; };
 		7A02CFA32361513600B49FAE /* UIScrollView+IGListKit.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF6A2361513400B49FAE /* UIScrollView+IGListKit.h */; };
 		7A02CFA52361513600B49FAE /* UICollectionView+IGListBatchUpdateData.m in Sources */ = {isa = PBXBuildFile; fileRef = 7A02CF6B2361513400B49FAE /* UICollectionView+IGListBatchUpdateData.m */; };
@@ -192,8 +190,6 @@
 		7A02CFD02361513600B49FAE /* IGListDebugger.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF792361513400B49FAE /* IGListDebugger.h */; };
 		7A02CFD22361513600B49FAE /* IGListBatchUpdates.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF7A2361513400B49FAE /* IGListBatchUpdates.h */; };
 		7A02CFD32361513600B49FAE /* IGListBatchUpdates.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF7A2361513400B49FAE /* IGListBatchUpdates.h */; };
-		7A02CFD52361513600B49FAE /* IGSystemVersion.m in Sources */ = {isa = PBXBuildFile; fileRef = 7A02CF7B2361513400B49FAE /* IGSystemVersion.m */; };
-		7A02CFD62361513600B49FAE /* IGSystemVersion.m in Sources */ = {isa = PBXBuildFile; fileRef = 7A02CF7B2361513400B49FAE /* IGSystemVersion.m */; };
 		7A02CFD82361513600B49FAE /* IGListBatchUpdateData+DebugDescription.m in Sources */ = {isa = PBXBuildFile; fileRef = 7A02CF7C2361513400B49FAE /* IGListBatchUpdateData+DebugDescription.m */; };
 		7A02CFD92361513600B49FAE /* IGListBatchUpdateData+DebugDescription.m in Sources */ = {isa = PBXBuildFile; fileRef = 7A02CF7C2361513400B49FAE /* IGListBatchUpdateData+DebugDescription.m */; };
 		7A02CFDB2361513600B49FAE /* IGListAdapterProxy.h in Headers */ = {isa = PBXBuildFile; fileRef = 7A02CF7D2361513400B49FAE /* IGListAdapterProxy.h */; };
@@ -535,7 +531,6 @@
 		7A02CF662361513400B49FAE /* IGListAdapterInternal.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGListAdapterInternal.h; sourceTree = "<group>"; };
 		7A02CF672361513400B49FAE /* IGListBindingSectionController+DebugDescription.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "IGListBindingSectionController+DebugDescription.h"; sourceTree = "<group>"; };
 		7A02CF682361513400B49FAE /* IGListCollectionViewLayoutInternal.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGListCollectionViewLayoutInternal.h; sourceTree = "<group>"; };
-		7A02CF692361513400B49FAE /* IGSystemVersion.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGSystemVersion.h; sourceTree = "<group>"; };
 		7A02CF6A2361513400B49FAE /* UIScrollView+IGListKit.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "UIScrollView+IGListKit.h"; sourceTree = "<group>"; };
 		7A02CF6B2361513400B49FAE /* UICollectionView+IGListBatchUpdateData.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "UICollectionView+IGListBatchUpdateData.m"; sourceTree = "<group>"; };
 		7A02CF6C2361513400B49FAE /* UICollectionViewLayout+InteractiveReordering.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "UICollectionViewLayout+InteractiveReordering.h"; sourceTree = "<group>"; };
@@ -553,7 +548,6 @@
 		7A02CF782361513400B49FAE /* IGListBatchUpdateState.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGListBatchUpdateState.h; sourceTree = "<group>"; };
 		7A02CF792361513400B49FAE /* IGListDebugger.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGListDebugger.h; sourceTree = "<group>"; };
 		7A02CF7A2361513400B49FAE /* IGListBatchUpdates.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGListBatchUpdates.h; sourceTree = "<group>"; };
-		7A02CF7B2361513400B49FAE /* IGSystemVersion.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = IGSystemVersion.m; sourceTree = "<group>"; };
 		7A02CF7C2361513400B49FAE /* IGListBatchUpdateData+DebugDescription.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "IGListBatchUpdateData+DebugDescription.m"; sourceTree = "<group>"; };
 		7A02CF7D2361513400B49FAE /* IGListAdapterProxy.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = IGListAdapterProxy.h; sourceTree = "<group>"; };
 		7A02CF7E2361513500B49FAE /* IGListAdapterUpdater+DebugDescription.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "IGListAdapterUpdater+DebugDescription.h"; sourceTree = "<group>"; };
@@ -871,8 +865,6 @@
 				7A02CF8D2361513600B49FAE /* IGListSectionMap+DebugDescription.m */,
 				7A02CF8E2361513600B49FAE /* IGListWorkingRangeHandler.h */,
 				7A02CF872361513500B49FAE /* IGListWorkingRangeHandler.mm */,
-				7A02CF692361513400B49FAE /* IGSystemVersion.h */,
-				7A02CF7B2361513400B49FAE /* IGSystemVersion.m */,
 				7A02CF8F2361513600B49FAE /* UICollectionView+DebugDescription.h */,
 				7A02CF752361513400B49FAE /* UICollectionView+DebugDescription.m */,
 				7A02CF772361513400B49FAE /* UICollectionView+IGListBatchUpdateData.h */,
@@ -1170,7 +1162,6 @@
 				7A02CF2E2361511100B49FAE /* IGListBindingSectionController.h in Headers */,
 				7A02CF3D2361511100B49FAE /* IGListCollectionViewLayoutCompatible.h in Headers */,
 				7A02CF402361511100B49FAE /* IGListAdapterUpdaterDelegate.h in Headers */,
-				7A02CFA02361513600B49FAE /* IGSystemVersion.h in Headers */,
 				7A02CEFE2361511100B49FAE /* IGListCollectionViewDelegateLayout.h in Headers */,
 				7A02CF5B2361511100B49FAE /* IGListAdapterUpdater.h in Headers */,
 				7A02CF252361511100B49FAE /* IGListAdapterUpdateListener.h in Headers */,
@@ -1244,7 +1235,6 @@
 				7A02CF5A2361511100B49FAE /* IGListAdapterUpdater.h in Headers */,
 				7A02CFA82361513600B49FAE /* UICollectionViewLayout+InteractiveReordering.h in Headers */,
 				7A02CFD22361513600B49FAE /* IGListBatchUpdates.h in Headers */,
-				7A02CF9F2361513600B49FAE /* IGSystemVersion.h in Headers */,
 				7A02CF452361511100B49FAE /* IGListAdapterPerformanceDelegate.h in Headers */,
 				7A02D0022361513600B49FAE /* IGListSectionControllerInternal.h in Headers */,
 				7A02CFC92361513600B49FAE /* UICollectionView+IGListBatchUpdateData.h in Headers */,
@@ -1686,7 +1676,6 @@
 				7A02CFEB2361513600B49FAE /* IGListBatchUpdates.m in Sources */,
 				7A02CF132361511100B49FAE /* IGListGenericSectionController.m in Sources */,
 				7A02CFA62361513600B49FAE /* UICollectionView+IGListBatchUpdateData.m in Sources */,
-				7A02CFD62361513600B49FAE /* IGSystemVersion.m in Sources */,
 				7A02CFC42361513600B49FAE /* UICollectionView+DebugDescription.m in Sources */,
 				7A02CFBE2361513600B49FAE /* IGListAdapterUpdater+DebugDescription.m in Sources */,
 				7A02CFAC2361513600B49FAE /* IGListReloadIndexPath.m in Sources */,
@@ -1786,7 +1775,6 @@
 				7A02CFEA2361513600B49FAE /* IGListBatchUpdates.m in Sources */,
 				7A02CF122361511100B49FAE /* IGListGenericSectionController.m in Sources */,
 				7A02CFA52361513600B49FAE /* UICollectionView+IGListBatchUpdateData.m in Sources */,
-				7A02CFD52361513600B49FAE /* IGSystemVersion.m in Sources */,
 				7A02CFC32361513600B49FAE /* UICollectionView+DebugDescription.m in Sources */,
 				7A02CFBD2361513600B49FAE /* IGListAdapterUpdater+DebugDescription.m in Sources */,
 				7A02CFAB2361513600B49FAE /* IGListReloadIndexPath.m in Sources */,

Source/IGListKit/IGListAdapter.m

@@ -10,7 +10,6 @@
 #import <IGListDiffKit/IGListAssert.h>
 #import <IGListKit/IGListAdapterUpdater.h>
 #import <IGListKit/IGListSupplementaryViewSource.h>
-#import <IGListKit/IGSystemVersion.h>
 
 #import "IGListArrayUtilsInternal.h"
 #import "IGListDebugger.h"
@@ -26,13 +25,6 @@ @implementation IGListAdapter {
 }
 
 - (void)dealloc {
-    // on iOS 9 setting the dataSource has side effects that can invalidate the layout and seg fault
-    if (!IGSystemVersionIsIOS9OrNewer()) {
-        // properties are assign for <iOS 9
-        _collectionView.dataSource = nil;
-        _collectionView.delegate = nil;
-    }
-
     [self.sectionMap reset];
 }
 

Source/IGListKit/Internal/UICollectionViewLayout+InteractiveReordering.m

@@ -11,7 +11,6 @@
 
 #import <IGListKit/IGListAdapterInternal.h>
 #import <IGListKit/IGListSectionController.h>
-#import <IGListKit/IGSystemVersion.h>
 
 @implementation UICollectionViewLayout (InteractiveReordering)
 
@@ -21,11 +20,6 @@ + (void)load
 {
     static dispatch_once_t onceToken;
     dispatch_once(&onceToken, ^{
-        // interactive reordering does not exist prior to iOS 9
-        if (!IGSystemVersionIsIOS9OrNewer()) {
-            return;
-        }
-
         Class layoutClass = [self class];
 
         // override implementation for targetIndexPathForInteractivelyMovingItem:withPosition: