Finally i got output.
UIButton *clickButton=sender;
UILabel *label=clickButton.titleLabel;
NSString *buttonText=label.text;
NSString *javaScript = [NSString stringWithFormat:@"var textField = document.activeElement;" "textField.value = textField.value+'%@';" "document.activeElement.form.submit();", buttonText];
[webView stringByEvaluatingJavaScriptFromString:javaScript];