Unusual behaviour of text field .Clear text field data on click event of button

When user click on button , I want to clear text field. How can i do this?

My code is as follows =>

textFieldName.tex开发者_如何学JAVAt = nil;
textViewAddress.text = nil;

But this code is not clearing the text field, but it clears the textView. Also when i use backspace button from keyboard of iphone it is not clearing textfield. If i write something in textfield it starts writing on top of existing characters.

Please help me friends. Thanks

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Maybe this would be sufficient

textFieldName.text = @"";
textViewAddress.text = @"";