Undo/Redo Operation doesn't work with Bold,italic, Background and Foreground text color in UITextview

Question

As User enter some text in UITextview, User applies some operation like Bold, italic, Underline, Bullet, Background and Foreground color to the specific text.When Undo/redo operation is applied, it will erase the whole word instead of eliminating bold/italic or foreground/background color of the text in textview.

Here's the code for it.

 [[txtViewNote undoManager] undo]; //Button Action Method for Undo

Answer 1

Finally I found third party code which perfectly meet my requirements i.e. to use This Text Editor which gives bullet,numbered,bold,italic and so on in simple way.