Provides explanations for check.

RxCocoa/iOS/UITextField+Rx.swift

@@ -25,6 +25,9 @@ extension UITextField : RxTextInput {
             getter: { textField in
                 textField.text ?? ""
             }, setter: { textField, value in
+                // This check is important because setting text value always clears control state
+                // including marked text selection which is imporant for proper input 
+                // when IME input method is used.
                 if textField.text != value {
                     textField.text = value
                 }

RxCocoa/iOS/UITextView+Rx.swift

@@ -53,6 +53,9 @@ extension UITextView : RxTextInput {
         }
 
         let bindingObserver = UIBindingObserver(UIElement: self) { (textView, text: String) in
+            // This check is important because setting text value always clears control state
+            // including marked text selection which is imporant for proper input 
+            // when IME input method is used.
             if textView.text != text {
                 textView.text = text
             }