Snippets

Testing chars entered by users in NSTextField

When the contents of a NSTextField are changed by the user, it is possible to check whether or not to accept the changes.

1. Subclass NSTextField

2. In your subclass implement the

        - (BOOL) textView: (NSTextView*) textView
        shouldChangeTextInRange: (NSRange) range
        replacementString: (NSString*) replacementString

method.

3. Within this method you can access to the replacementString as an NSString, or as char with the following line:

        char c = *([replacementString cString] + 0);  

4. You should return YES or NO depending on whether you accept the replacement string.

Limiting text input length in NSTextField

(based on Alexander Malmberg's snippet)

1. Subclass NSTextField

2. In your subclass implement the

        - (BOOL) textView: (NSTextView*) textView
        shouldChangeTextInRange: (NSRange) range
        replacementString: (NSString*) replacementString

method.

3. Also create an instance variable setting method:

         - (void) setMaxLength: (int) ml
         {
            maxLength = ml;
         } 

4. Then fill your implementation of textView:shouldChangeTextInRange:replacementString: with the following code:

         int newLength;
         /* The exact change isn't known. Disallow the change to be safe. */
          if (range.location == NSNotFound)
               return NO;
          newLength=[[textView textStorage] length]+[replacementString length]-range.length;
          if (newLength>maxLength)
               return YES; //allowing
          else
               return NO; // not allowing