在UITextView中获取当前键入的单词

Question

I want to get the currently typed word in a UITextView . A way to get a completely typed word can be found here UITEXTVIEW: Get the recent word typed in uitextview , however, I want to get the word while it is being typed (no matter where it is typed, beginning, middle, end of UITextView ).

I guess what defines a word being typed is a whitespace character followed by alphanumeric characters, or if the current location (somehow to figure out with range.location ) is the beginning of the UITextView then whatever follows up should be considered as word as well. A word is finished being typed when another whitespace character follows.

I tried with:

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

but I have a problem finding the correct range.

In short again: I need to find the substring in a UITextView , where substring is the currently typed word.

EDIT : Because the question came up. I'm using NSLayoutManager and bind a NSTextContainer to it, which then is passed as layoutManager to a NSTextStorage .

EDIT2 : The main problem with (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text is that the range.location is not the same as the indicator is, but always 1 less. If the cursor is at position 1, after typing one letter, range.location would return 0. Any way around this? In addition the text attribute of UITextView seems to be off by 1 as well. When the text is foobar and I output the UITextView.text then I get fooba instead. Therefore range.location+1 returns the exception Range {0, 1} out of bounds; string length 0' Range {0, 1} out of bounds; string length 0'

EDIT3 : Maybe it is easier to get my wanted result with the NSTextStorage instead of UITextView ?

Answer 1

The following is an example of a skeletal structure that uses UITextInput and UITextInputTokenizer to give the word that is being currently typed/edited.

- (void) textViewDidChange:(UITextView *)textView {

    NSRange selectedRange = textView.selectedRange;

    UITextPosition *beginning = textView.beginningOfDocument;
    UITextPosition *start = [textView positionFromPosition:beginning offset:selectedRange.location];
    UITextPosition *end = [textView positionFromPosition:start offset:selectedRange.length];

    UITextRange* textRange = [textView.tokenizer rangeEnclosingPosition:end withGranularity:UITextGranularityWord inDirection:UITextLayoutDirectionLeft];

    NSLog(@"Word that is currently being edited is : %@", [textView textInRange:textRange]);
}

This will give you the entire word that is currently being typed.

For instance if you are typing input and have typed inp it will give you inp . Further if you are in the middle of the word middle and change it to midddle , it will give you midddle . The trick here is tokenizing .

I have placed the code inside textViewDidChange: so that you get the word after it's been typed/edited. If you want it before the last character change (ie the word that is about to be changed), place the code in textView:shouldChangeTextInRange:replacementText: .

PS: You will have to handle edge cases like sentences and paragraphs being pasted/removed. You can modify this code to get characters/sentences/paragraphs etc, instead of just words by changing the granularity. Look into the declaration of UITextGranularity ENUM for more options:

typedef NS_ENUM(NSInteger, UITextGranularity) {
    UITextGranularityCharacter,
    UITextGranularityWord,
    UITextGranularitySentence,
    UITextGranularityParagraph,
    UITextGranularityLine,
    UITextGranularityDocument
};

Answer 2

You can simply extend UITextView and use following method which returns the word around the current location of cursor:

extension UITextView {

    func editedWord() -> String {

        let cursorPosition = selectedRange.location
        let separationCharacters = NSCharacterSet(charactersInString: " ")

        // Count how many actual characters there are before the cursor.
        // Emojis/special characters can each increase selectedRange.location
        // by 2 instead of 1

        var unitCount = 0
        var characters = 0
        while unitCount < cursorPosition {

            let char = text.startIndex.advancedBy(characters)
            let int = text.rangeOfComposedCharacterSequenceAtIndex(char)
            unitCount = Int(String(int.endIndex))!
            characters += 1
        }


        let beginRange = Range(start: text.startIndex.advancedBy(0), end: text.startIndex.advancedBy(characters))
        let endRange = Range(start: text.startIndex.advancedBy(characters), end: text.startIndex.advancedBy(text.characters.count))

        let beginPhrase = text.substringWithRange(beginRange)
        let endPhrase = text.substringWithRange(endRange)

        let beginWords = beginPhrase.componentsSeparatedByCharactersInSet(separationCharacters)
        let endWords = endPhrase.componentsSeparatedByCharactersInSet(separationCharacters)

        return beginWords.last! + endWords.first!
    }
}

Answer 3

The UITextView delegate method : -textView:textView shouldChangeTextInRange:range replacementText:text what actaully does is that it asks whether the specified text should be replaced in the text view in the specified range of textView.text .

This method will be invoked each time when we type a charactor before updating that to the text view. That is why you are getting the range.location as 0, when you type the very first character in the textView .

Only if the return of this method is true, the textView is getting updated with what we have typed in the textView .

This is the definition of the parameters of the -textView:textView shouldChangeTextInRange:range replacementText:text method as provided by apple:

range :- The current selection range. If the length of the range is 0, range reflects the current insertion point. If the user presses the Delete key, the length of the range is 1 and an empty string object replaces that single character.
text :- The text to insert.

So this is what the explanation for the method and your requirement can meet like as follows:

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
        //Un-commend this check below :If you want to detect the word only while new line or white space charactor input 
        //if ([text isEqualToString:@" "] || [text isEqualToString:@"\n"])
        //{
            // Getting the textView text upto the current editing location
            NSString * stringToRange = [textView.text substringWithRange:NSMakeRange(0,range.location)];

            // Appending the currently typed charactor
            stringToRange = [stringToRange stringByAppendingString:text];

            // Processing the last typed word 
            NSArray *wordArray       = [stringToRange componentsSeparatedByString:@" "];
            NSString * wordTyped     = [wordArray lastObject];

            // wordTyped will give you the last typed object
            NSLog(@"\nWordTyped :  %@",wordTyped);
        //}
        return YES;
}

Answer 4

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSString *string = [textView.text stringByReplacingCharactersInRange:range withString:text];

    if ([text isEqualToString:@"\n"] || [text isEqualToString:@" "])
    {
        NSString *currentString = [string stringByReplacingOccurrencesOfString:@"\n" withString:@" "];

        NSLog(@"currentWord==> %@",currentString);
    }

    return YES;
}

Answer 5

Your range parameter from the - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text delegate method points at the exact place you change the UITextView string value.

The location property of the structure points to the changing string index, that's simple. The length not usually equals to text.length , be careful, user may select characters from the string to replace it with another string.