//This method looks for the recent string entered by user and then takes appropriate action.

     - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

 //Look for Space or any specific string such as a space
if ([text isEqualToString:@" "]) {
NSMutableCharacterSet *workingSet = [[NSCharacterSet whitespaceAndNewlineCharacterSet]   mutableCopy];

  NSRange newRange = [self.myTextView.text rangeOfCharacterFromSet:workingSet
                                     options:NSBackwardsSearch
                                     range:NSMakeRange(0, (currentLocation - 1))];

 //The below code could be done in a better way...
 UITextPosition *beginning = myTextView.beginningOfDocument;
 UITextPosition *start = [myTextView positionFromPosition:beginning offset:currentLocation];
 UITextPosition *end = [myTextView positionFromPosition:beginning   offset:newRangeLocation+1];
 UITextRange *textRange = [myTextView textRangeFromPosition:end toPosition:start];

 NSString* str = [self.myTextView textInRange:textRange]; 
}
}