Getting the word touched in a UILabel/UITextView

Question

What I\'d like to do is to create a text-container component that is able to indicate what is the nearest word when there\'s is a touch on it (i.e. the word \"behind\" the t

Answer 1

Though this is an old question, but i thought this might be of some help.

Since learning core text was huge, i opted for GLTapDemo by German Laullon

With a few changes , this works great for detecting touched word on UILabel.

Answer 2

After searching a bit I have written a code for this. Code will work for UITextView and UILabel.
Just download VSWordDetector.zip then unzip it and drag & drop the folder VSWordDetector into your project.
There are two files VSWordDetector.h and VSWordDetector.m
#import VSWordDetector.h in your ViewController class.

@property (strong, nonatomic) VSWordDetector *wordDetector;

Note: Make its property don't take as locally.

Now its ready for you, Just add it on textViews or Labels

-(void)viewDidLoad
{
   self.wordDetector = [[VSWordDetector alloc] initWithDelegate:self];
   [self.wordDetector addOnView:textView];
   [self.wordDetector addOnView:label];
}

-(void)wordDetector:(VSWordDetector *)wordDetector detectWord:(NSString *)word
{
   NSLog(@"Detected Word: %@", word);
}

This delegate method will be call when you will tap on connected label or textView.

EDIT: Sample Code for VSWordDetector.

SUGGESTED EDIT: If you don't want to download the sample code here is the code for both file. Please see this gist file VSWordDetector.

Answer 3

(There is a link to a sample code project in your linked post that does contain some useful sample code, but I will outline the process for you here too.)

In short, you are going to need to use Core Text, which is Apple's advanced C-based text handling framework that backs all sophisticated text layout in iOS and OS X.

The full code is going to be somewhat involved, but key methods you are going to want to look at are:

CTFramesetterCreateWithAttributedString() - use this, in conjunction with an NSAttributedString that you will get from your label's text - to create the framesetter

CTFramesetterCreateFrame() - use this to get a CTFrameRef for your text from the above framesetter. You will need to create a CGPathRef using your label bounds to do this.

CTFrameGetLines(), CTFrameGetLineOrigins() - use these to get CTLineRefs corresponding to the typeset lines, and the coordinates of the line origins, respectively, then use CTLineGetStringIndexForPosition() to find the character index at a touch location.

You can then use this character index (in the line's reference frame) to work backward and find the actual character/word/etc within your full string.

Don't forget that matters are complicated by a couple issues:

1. If you use UILabel's native drawing you will have to take care to perfectly match your typesetting metrics, which can be cumbersome since most of the objects (e.g. CTFontRef) are not toll-free bridged with their UIKit counterparts. Implementing your own drawing may, sometimes, be easier, which will guarantee metric matching.

2. Core Text uses an inverted coordinate system with respect to the normal iOS drawing system. If you are getting wacky results, and especially if you do your own drawing, this is something to take a look at.

Not the easiest task in the world, but far from impossible. Good luck!