Enable backwards compatibility when compiling with Xcode 14 (#329)

* Enable backwards compatibility when compiling with Xcode 14

This will still mean that the bug addressed in #314 will persist, but will allow consumers bound to older Xcode versions to continue to update the rest of the codebase and its dependencies

* Add end-of-file new lines

* Safe-guard usage as well

Author: eliperkins

Sources/Runestone/Library/UITextInput+Helpers.swift

@@ -1,5 +1,7 @@
 import UIKit
 
+#if compiler(>=5.9)
+
 @available(iOS 17, *)
 extension UITextInput where Self: NSObject {
     var sbs_textSelectionDisplayInteraction: UITextSelectionDisplayInteraction? {
@@ -17,3 +19,5 @@ extension UITextInput where Self: NSObject {
         return interactionAssistant.value(forKey: selectionViewManagerKey) as? UITextSelectionDisplayInteraction
     }
 }
+
+#endif

Sources/Runestone/Library/UITextSelectionDisplayInteraction+Helpers.swift

@@ -1,8 +1,12 @@
 import UIKit
 
+#if compiler(>=5.9)
+
 @available(iOS 17, *)
 extension UITextSelectionDisplayInteraction {
     func sbs_enableCursorBlinks() {
         setValue(true, forKey: "rosruc".reversed() + "Blinks")
     }
 }
+
+#endif

Sources/Runestone/TextView/Core/TextView.swift

@@ -1234,10 +1234,12 @@ private extension TextView {
             isInputAccessoryViewEnabled = true
             textInputView.removeInteraction(nonEditableTextInteraction)
             textInputView.addInteraction(editableTextInteraction)
+            #if compiler(>=5.9)
             if #available(iOS 17, *) {
                 // Workaround a bug where the caret does not appear until the user taps again on iOS 17 (FB12622609).
                 textInputView.sbs_textSelectionDisplayInteraction?.isActivated = true
             }
+            #endif
         }
     }
 
@@ -1390,10 +1392,12 @@ extension TextView: TextInputViewDelegate {
             if !view.viewHierarchyContainsCaret && self.editableTextInteraction.view != nil {
                 view.removeInteraction(self.editableTextInteraction)
                 view.addInteraction(self.editableTextInteraction)
+                #if compiler(>=5.9)
                 if #available(iOS 17, *) {
                     self.textInputView.sbs_textSelectionDisplayInteraction?.isActivated = true
                     self.textInputView.sbs_textSelectionDisplayInteraction?.sbs_enableCursorBlinks()
                 }
+                #endif
             }
         }
     }