TweetFollow Us on Twitter

Jan 02 MacOSX

Volume Number: 18 (2002)
Issue Number: 01
Column Tag: Mac OS X

Smart Quotes

by ©2001 Andrew C. Stone. All Rights Reserved.

Adding automated curly quotes to Cocoa's Text system

Cocoa's Text System architecture is open, open-ended, and contains hooks for easy behavior modification. Because Cocoa Text is a unicode based system, it is by default international and lets your applications work correctly in a variety of scripts and languages. This article will teach you how to inspect the user's typed stream of keys, and convert straight quotes to open and closed curly quotes as the user types:

"Love is ‘THE' answer," she said.

Remembering all the modifier keys to create a curly quote is troublesome for end users, so we'll add the functionality to replace the boring straight quotes with fancy curly ones as they type. We'll also include a mechanism to "toggle through" the various options for those odd border cases, such as words beginning with a quote: 'Tis.

The Unicode

Cocoa's Text system relies on Unicode which allows each character in most standard font to be mapped to a unique short integer, a "unichar" defined in NSString.h:

typedef unsigned short unichar;

For example, each glyph in the Symbol font and Dingbats font are represented by unicode characters. The HTML standard also allows use of unicode characters, and here are the Unicode and HTML codes (which correspond to the unicode value) for curly quotes:

Character Unicode HTML Name How to type in manually
" 8220 “ double open quote Option-[
' 8216 ‘ single open quote Option-]
" 8221 ” double close Option-Shift-[
' 8217 ’ single close Option-Shift-]

Now that we know what will replace the straight quotes, we need a strategy for determining if a quote should be open or closed! It turns out that a very simple heuristic will work:

if character typed is a Straight Quote then

If it's the first character or is preceded by whitespace, turn it into Open Curly Quote

       else turn it into Close Curly Quote

So, when a newline, tab or space precedes a quote, it's probably an open quote. Note that this fails with ‘Tis! So, let's refine our heuristic to include a mechanism to "move through" the options straight, open and closed if the user has the quote in question solely selected:

if character typed is ‘ or " then

if selection contains a  single quote of any style,  replace with the next style in a loop (straight -> 
open -> closed -> straight and so on)

    else

If it's the first character or is preceded by whitespace, turn into Open Quote (single or double)

       else turn it into Close Quote

We have one more feature to add - the user should be able to DIRECTLY type in a straight quote when fancy quotes are enabled. We'll let them do this by changing any typed fancy quote to its straight counterpart (see How to type in manually in table above).

The Hook

One aspect of Cocoa that reigns supreme is the ease in which functionality can added, as well as the many different approaches that can be taken to accomplish the same task.

Where you put code depends on your architectural design. While you can always override a class, it's often easier to simply look at the "Delegate Methods" defined in various classes. These methods are optional: if an object, such as a text view, has a delegate, and that delegate implements one of these methods, then that method will be called at the appropriate time by the text view. If you overrode "keyDown" in NSTextView in a subclass, your text wouldn't swap the quotes on pasted text, since pasting does not call keyDown! So, instead we'll use this NSTextView delegate method that gets called anytime text is inserted either via keys or paste:

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

    // Delegate only.  If characters are changing, replacementString is what will replace the 
    affectedCharRange.  If attributes only are changing, replacementString will be nil.

This delegate method will work for us since we are only replacing single characters with another single character. If I had designed this method, instead of returning a boolean, I would have had this method return the actual new string to be inserted. Working with the method the way it is, we'll simply brute force stick in the character of our choice and return NO.

The Code

// Code is always more readable if you can turn the magic numbers into English!
#define SINGLE_QUOTE      ‘\''
#define SINGLE_OPEN_QUOTE   8216
#define SINGLE_CLOSE_QUOTE   8217
#define DOUBLE_QUOTE      ‘"‘
#define DOUBLE_OPEN_QUOTE   8220
#define DOUBLE_CLOSE_QUOTE   8221

// Smart Quote support - in our NSTextView's delegate class, we implement this method
// Be sure to connect the TextView's delegate outlet to your custom delegate class in Interface Builder
// or use  [myTextView setDelegate:self]; in your delegate class so this gets called:

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

    // Delegate only.  If characters are changing, replacementString is what will replace the 
    affectedCharRange.  If attributes only are changing, replacementString will be nil.
{

   // if we're just changing text attributes then we don't enter our processing loop
   // Also, provide a defaults mechanism to turn this fancy quoting off:
   
    if (replacementString && [[NSUserDefaults standardUserDefaults]boolForKey:SmartQuotes]) {
    
       // This is what is in our text object before anything is added:
        NSString *text = [[textView textStorage] string];
   
      // We want to know if we are at the very first character:
        unsigned int textLength = [text length];
   
      // how much are  we actually adding at this time:
        unsigned int i, length = [replacementString length];
        unichar c;
   
      // Should we change the string, we'll use this mutable string to hold the new values:
      // If it's non-nil when we get done, that means we've got work to do!
        NSMutableString *s = nil;
            
       // First, our toggle through mechanism:
        // special case: one char typed OVER a smart quote -> toggle them around 3 way
        // plain -> open -> closed -> plain
        // First deal with the case where they want another type of quote or a plain quote!
        if (length == 1 &&  affectedCharRange.length == 1) {
   
            if (((c = [text characterAtIndex:affectedCharRange.location])==DOUBLE_OPEN_QUOTE) || 
            (c == SINGLE_OPEN_QUOTE)) {
                // they had an open quote -> make it a closed one
                s = [NSString stringWithFormat:@"%C", c == DOUBLE_OPEN_QUOTE ? 
                DOUBLE_CLOSE_QUOTE : SINGLE_CLOSE_QUOTE];
      
            } else if (c == DOUBLE_CLOSE_QUOTE || c == SINGLE_CLOSE_QUOTE) {
                // they had a closed quote -> make it plain
                s = [NSString stringWithFormat:@"%C", c == DOUBLE_CLOSE_QUOTE  ? 
                DOUBLE_QUOTE : SINGLE_QUOTE];
      
            } else if (c == SINGLE_QUOTE || c == DOUBLE_QUOTE) {
             // they had a straight quote -> make it open
                 s = [NSString stringWithFormat:@"%C", c == SINGLE_QUOTE  ?  
                 SINGLE_OPEN_QUOTE : DOUBLE_OPEN_QUOTE];
           }
        } else {
   
        // otherwise go through replacement string one by one - paste can put in many characters at 
        one time!
            NSCharacterSet *startSet = [NSCharacterSet whitespaceAndNewlineCharacterSet];
            for (i = 0; i < length; i++) {
       
                unichar theChar = [replacementString characterAtIndex:i];
                unichar previousChar;
                
            // Find out the character which preceeds this one - context is everything!
                if(i == 0) {
                    if (affectedCharRange.location == 0 || textLength==0) previousChar = 0; 
                    // first char
                    else previousChar = [text characterAtIndex:affectedCharRange.location - 1];
                } else previousChar = [replacementString characterAtIndex:i-1];
                
            // When we encounter a straight quote, we decide whether it should be open or closed:
                if ((theChar == SINGLE_QUOTE) || (theChar == DOUBLE_QUOTE)){
      
               // lazily allocate the mutable string if we find something interesting
                    if (!s) s = [NSMutableString stringWithString:replacementString]; 
                    
                    if (previousChar == 0 || [startSet characterIsMember:previousChar] || 
                    (previousChar == DOUBLE_OPEN_QUOTE && theChar == SINGLE_QUOTE) || 
                    (previousChar == SINGLE_OPEN_QUOTE && theChar == DOUBLE_QUOTE))
                        c =  (theChar  == SINGLE_QUOTE  ?  SINGLE_OPEN_QUOTE : DOUBLE_OPEN_QUOTE);
                    else c =  (theChar  == SINGLE_QUOTE  ?  SINGLE_CLOSE_QUOTE : DOUBLE_CLOSE_QUOTE);
                    
                    [s replaceCharactersInRange:NSMakeRange(i,1) 
                    withString:[NSString stringWithFormat:@"%C", c]];
          
                } else if ((i==0) && (length == 1)) {
      
                    // we don't want to do this unless they are typing - paste may contain curly's 
                    already!
                    // reverse the meaning - they want to type in a plain one from the keyboard 
                    directly:
          
                    if ((theChar == SINGLE_CLOSE_QUOTE) || (theChar == SINGLE_OPEN_QUOTE)) {
                            s = [NSMutableString stringWithFormat:@"%C", SINGLE_QUOTE];
                    } else if ((theChar == DOUBLE_CLOSE_QUOTE) || (theChar == DOUBLE_OPEN_QUOTE)) {
                            s = [NSMutableString stringWithFormat:@"%C", DOUBLE_QUOTE];
                    }
                }
                        
            }
        }
        if (s) {
                // We'll be responsible for inserting the changed text ourselves
            // ideally, this method would return the string desired, but it doesn't
            // so we'll just pop the changes in directly ourselves:
                [[textView textStorage] replaceCharactersInRange:affectedCharRange withString:s];
                return NO;               
        }
    }
    // Otherwise, let the text system insert the text as typed...
    return YES;
}

Conclusion

The Cocoa Text system is easy to use and very extensible in a straightforward manner. An improvement you might consider for this smart quoting technique is to allow for internationalization. For example, in Germany, the open quote is along the text baseline, and other languages might use ‹› or other characters for quoting. To accomplish this, you would use NSLocalizedStringFromTable() and create an entry in the .strings file for each of the quotes in the languages that you support - refer to my article on Localization in MacTech a few months back for more information.


Andrew Stone, CEO of Stone Design, www.stone.com, has been coding in Cocoa as an independent software developer for over 13 years.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

TotalFinder 1.12.2 - Adds tabs, hotkeys,...
TotalFinder is a universally acclaimed navigational companion for your Mac. Enhance your Mac's Finder with features so smart and convenient, you won't believe you ever lived without them. Features... Read more
Duet 2.3.0.3 - Use your iPad as an exter...
Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable. Note: This app requires a $9.99 iOS companion app. Version 2.3.0.3:... Read more
FileMaker Pro Advanced 18.0.3 - Powerful...
FileMaker Pro Advanced is the tool you use to create a custom app. You also use FileMaker Pro Advanced to access your app on a computer. Start by importing data from a spreadsheet or using a built-in... Read more
OsiriX Lite 10.0.6 - 3D medical image pr...
OsiriX Lite is an image processing software dedicated to DICOM images (".dcm" / ".DCM" extension) produced by medical equipment (MRI, CT, PET, PET-CT, ...) and confocal microscopy (LSM and BioRAD-PIC... Read more
Ableton Live 10.1.5 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Burn 2.7.8 - Easily burn data, audio, vi...
Burn... There are a lot of ways to approach burning discs. Burn keeps it simple, but still offers a lot of advanced options. Create data discs with advanced data settings like, file permissions, the... Read more
Malwarebytes 4.0.30.3073 - Adware remova...
Malwarebytes (was AdwareMedic) helps you get your Mac experience back. Malwarebytes scans for and removes code that degrades system performance or attacks your system. Making your Mac once again your... Read more
Acorn 6.5.3 - Bitmap image editor.
Acorn is a new image editor built with one goal in mind - simplicity. Fast, easy, and fluid, Acorn provides the options you'll need without any overhead. Acorn feels right, and won't drain your bank... Read more
Fantastical 2.5.13 - Create calendar eve...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event... Read more
A Better Finder Rename 11.05 - File, pho...
A Better Finder Rename is the most complete renaming solution available on the market today. That's why, since 1996, tens of thousands of hobbyists, professionals and businesses depend on A Better... Read more

Latest Forum Discussions

See All

Eternal Warfare is a new idle clicker fo...
Idle games are a popular genre on mobile, they might not be to everyone's taste but they're made with such regularity and receive a lot of downloads, so it's hard to argue it's not big business. Eternal Warfare is set to join the sea of idle games... | Read more »
New heroes and balance updates set to ar...
It feels like Hearthstone: Battlegrounds only launched yesterday, and already the auto batter addition to Blizzard's megahit card game is set to receive new heroes and balance updates. [Read more] | Read more »
Pre-register for Hello Kitty AR: Kawaii...
Hello Kitty — the cute cat that launched a multi-billion-pound franchise — has been brought to life… sort of. Sanrio has teamed up with the Bublar Group to create a new mobile game that uses AR tech to turn the real world into Hello Kitty’s... | Read more »
Gorgeous and tranquil puzzler Spring Fal...
One-man indie studio SPARSE//GameDev has now launched its tranquil puzzler, Spring Falls. It's described as "a peaceful puzzle game about water, erosion, and watching things grow". [Read more] | Read more »
Black Desert Mobile gets an official rel...
Pearl Abyss has just announced that its highly-anticipated MMO, Black Desert Mobile, will launch globally for iOS and Android on December 11th. [Read more] | Read more »
Another Eden receives new a episode, cha...
Another Eden, WFS' popular RPG, has received another update that brings new story content to the game alongside a few new heroes to discover. [Read more] | Read more »
Overdox guide - Tips and tricks for begi...
Overdox is a clever battle royale that changes things up by adding MOBA mechanics and melee combat to the mix. This new hybrid game can be quite a bit to take in at first, so we’ve put together a list of tips to help you get a leg up on the... | Read more »
Roterra Extreme - Great Escape is a pers...
Roterra Extreme – Great Escape has been described by developers Dig-It Games as a mini-sequel to their acclaimed title Roterra: Flip the Fairytale. It continues that game's tradition of messing with which way is up, tasking you with solving... | Read more »
Hearthstone: Battlegrounds open beta lau...
Remember earlier this year when auto battlers were the latest hotness? We had Auto Chess, DOTA Underlords, Chess Rush, and more all gunning for our attention. They all had their own reasons to play, but, at least from where I'm standing, most... | Read more »
The House of Da Vinci 2 gets a new gamep...
The House of Da Vinci launched all the way back in 2017. Now, developer Blue Brain Games is gearing up to deliver a second dose of The Room-inspired puzzling. Some fresh details have now emerged, alongside the game's first official trailer. [Read... | Read more »

Price Scanner via MacPrices.net

B&H offers $100 discounts on 4-Core and 6...
B&H Photo has new 4-Core and 6-Core Mac minis in stock and on sale today for $100 off Apple’s MSRP. Prices start at $699. Overnight shipping is free to many addresses in the US: – 3.6GHz Quad-... Read more
Save $200 today on a 2019 13″ MacBook Air wit...
Apple has a full line of Certified Refurbished 2019 13″ MacBook Airs available starting at only $929 and up to $200 off the cost of new Airs. Each MacBook features a new outer case, comes with a... Read more
New Verizon Pre-Black Friday 2019 deal: Buy o...
Buy one new Apple iPhone 11 model or 2018 iPhone XS model at Verizon and get a second one for free. One new line of service required. Offer is valid from November 21, 2019 to November 27, 2019. Here... Read more
AirPods with Wireless Charging Case on sale t...
Abt Electronics has 2019 AirPods with the Wireless Charging Case on sale today for $163 shipped. Their price is $36 off Apple’s MSRP, and it’s currently the cheapest price for these AirPods from any... Read more
Apple continues to offer 2017 13″ Dual-Core n...
Apple has Certified Refurbished 2017 13″ 2.3GHz Dual-Core non-Touch Bar MacBook Pros still available starting at $1019. An standard Apple one-year warranty is included with each model, outer cases... Read more
Save up to $120 on the new 16″ MacBook Pro at...
Apple’s resellers are starting to receive stock of new 16″ MacBook Pros, and the first set of sales & deals are now available: (1) Amazon 16″ MacBook Pros start on sale for $100-$116 off Apple’s... Read more
Apple Watch Series 3 models on sale at Amazon...
Amazon has Apple Watch Series 3 GPS models on sale for $30 off MSRP, starting at only $169. There prices are the lowest we’ve ever seen for these models from any Apple reseller. Choose Amazon as the... Read more
The ‘Mac Potpourri’ Mailbag: Edition #1- Info...
COMMENTARY: 11.20.19- Welcome to the inaugural edition of the “Mac Potpourri” Mailbag where we take a look at correspondence received from readers of this column from all over the world who write in... Read more
13″ 2.4GHz MacBook Pros available for up to $...
Apple has a full line of Certified Refurbished 2019 13″ 2.4GHz 4-Core Touch Bar MacBook Pros available starting at $1529 and up to $300 off MSRP. Apple’s one-year warranty is included, shipping is... Read more
New at T-Mobile: Switch to T-Mobile, and get...
T-Mobile is offering a free 64GB iPhone 8 for new customers who switch to T-Mobile and open a new line of service. Eligible trade-in required, and discount applied over a 24 month period. The fine... Read more

Jobs Board

Best Buy *Apple* Computing Master - Best Bu...
**747303BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Store NUmber or Department:** 001413-Cypress-Store **Job Description:** **What Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**743221BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000230-Greenwood-Store **Job Description:** At Best Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**747338BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000254-Superstition Springs-Store **Job Read more
Best Buy *Apple* Computing Master - Best Bu...
**745516BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Store Associates **Store NUmber or Department:** 001101-Manhattan-Store **Job Read more
Best Buy *Apple* Computing Master - Best Bu...
**746655BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Store NUmber or Department:** 002518-Atlantic Center-Store **Job Description:** Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.