Add RichTextView input callback

[HaidyCao]

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• Feature Request
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Description

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I want listen content of the RichTextView when input or delete some content.

[aelkady]

@HaidyCao could you elaborate more on this? Are you essentially saying that you want to be hooked up to the delegate methods of the UITextView subviews in the RichTextView?

[HaidyCao]

Thank you. But I need to get the child of RichTextView as UITextView and hook the delegate of that.

[aelkady]

@HaidyCao I have opened #91 to address this issue, feel free to take a look and make any changes if you feel it's necessary.