PPLabel

UIlabel subclass with ability to detect touches on individual letters

The advantage os this implementation is that it uses the ability of UILabel to display NSAttributedString on iOS 6.0+. There is no hacking of the drawRect: or drawText: method of UILabel. CoreText is used only to detect touched letters.

Why to use PPLabel

Draws text exactly the same way as UILabel
Dead simple implementation, look at the source code.

PPLabel requires iOS 6+

Getting Started

Cocoapods

CocoaPods is the recommended way to add PPLabel to your project.

Add a pod entry for PPLabel to your Podfile pod 'PPLabel', '~> 0.5'
Install the pod(s) by running pod install.
Include PPLabel wherever you need it with #import <PPLabel.h>.

Source Files / Git Submodule

Obtain the last version of PPLabel from the master branch.
Add PPLabel.h and PPLabel.m into your project
Import CoreText framework into your project.
Have a look at the example project and enjoy PPLabel.

Examples

Usage

The example project highlights touched words in a label. This behaviour can be modified to highlight touched links, hashtags or whatever you want.

//
//  ViewController.h
//  PPLabel
//
//  Created by Petr Pavlik on 12/28/12.
//  Copyright (c) 2012 Petr Pavlik. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "PPLabel.h"

@interface ViewController : UIViewController <PPLabelDelegate>

@property (weak, nonatomic) IBOutlet PPLabel *label;

@end

//
//  ViewController.m
//  PPLabel
//
//  Created by Petr Pavlik on 12/28/12.
//  Copyright (c) 2012 Petr Pavlik. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@property(nonatomic) NSRange highlightedRange;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    
    self.label.delegate = self;
}

#pragma mark PPLabelDelegate

- (BOOL)label:(PPLabel *)label didBeginTouch:(UITouch *)touch onCharacterAtIndex:(CFIndex)charIndex {
    
    [self highlightWordContainingCharacterAtIndex:charIndex];
    return NO;
}

- (BOOL)label:(PPLabel *)label didMoveTouch:(UITouch *)touch onCharacterAtIndex:(CFIndex)charIndex {
    
    [self highlightWordContainingCharacterAtIndex:charIndex];
    return NO;
}

- (BOOL)label:(PPLabel *)label didEndTouch:(UITouch *)touch onCharacterAtIndex:(CFIndex)charIndex {
    
    [self removeHighlight];
    return NO;
}

- (BOOL)label:(PPLabel *)label didCancelTouch:(UITouch *)touch {
    
    [self removeHighlight];
    return NO; 
}

#pragma mark --

- (void)highlightWordContainingCharacterAtIndex:(CFIndex)charIndex {
    
    if (charIndex==NSNotFound) {
        
        //user did nat click on any word
        [self removeHighlight];
        return;
    }
    
    NSString* string = self.label.text;
    
    //compute the positions of space characters next to the charIndex
    NSRange end = [string rangeOfString:@" " options:0 range:NSMakeRange(charIndex, string.length - charIndex)];
    NSRange front = [string rangeOfString:@" " options:NSBackwardsSearch range:NSMakeRange(0, charIndex)];
    
    if (front.location == NSNotFound) {
        front.location = 0; //first word was selected
    }
    
    if (end.location == NSNotFound) {
        end.location = string.length-1; //last word was selected
    }
    
    NSRange wordRange = NSMakeRange(front.location, end.location-front.location);
    
    if (front.location!=0) { //fix trimming
        wordRange.location += 1;
        wordRange.length -= 1;
    }
    
    if (wordRange.location == self.highlightedRange.location) {
        return; //this word is already highlighted
    }
    else {
        [self removeHighlight]; //remove highlight on previously selected word
    }
    
    self.highlightedRange = wordRange;
    
    //highlight selected word
    NSMutableAttributedString* attributedString = [self.label.attributedText mutableCopy];
    [attributedString addAttribute:NSBackgroundColorAttributeName value:[UIColor redColor] range:wordRange];
    self.label.attributedText = attributedString;
}

- (void)removeHighlight {
    
    if (self.highlightedRange.location != NSNotFound) {
        
        //remove highlight from previously selected word
        NSMutableAttributedString* attributedString = [self.label.attributedText mutableCopy];
        [attributedString removeAttribute:NSBackgroundColorAttributeName range:self.highlightedRange];
        self.label.attributedText = attributedString;
        
        self.highlightedRange = NSMakeRange(NSNotFound, 0);
    }
}

@end

Credits

Many thanks to Mattt Thomson and his TTTAttributedLabel. It was a big inspiration.

Contact

@ptrpavlik

petrpavlik on App.net

petrpavlik@me.com

License

PPLabel is available under the MIT license.

mjtong/PPLabel