TweetFollow Us on Twitter

Using NSParagraphStyle

Volume Number: 19 (2003)
Issue Number: 8
Column Tag: Cocoa

Using NSParagraphStyle

How to programmatically set tabs and more in an NSTextView

by Clark Jackson

The need to become acquainted with NSParagraphStyle occurred when I attempted to automate some reporting. At times "enterprise" computing stands in contrast to typical "consumer" computing because the latter is user-centric while the former is report-centric. For example, consumer computing facilitates lots of user control whereas enterprise computing just wants to-generate-reports-unattended-at-midnight-thank-you. Since much of the text system in Cocoa "just works" for the user, the details of how to let the computer take control in making a report are often left a mystery. Let's shed a little light on some of that mystery.

What we need is to know how to use just one piece of Cocoa's extensive and capable text system that will allow a program to format text inside an NSTextView. The key is using the NSParagraphStyle class.

Some preliminaries

Explaining Interface Builder and Project Builder is beyond the scope of this article. Suffice it to say, the project uses the Model-View-Controller paradigm employing MyModel, MyWindowController, and NSTextView classes. Here's what the view looks like:


Figure 1. The interface window containing an NSTextView.

The only thing noteworthy about this window is that it contains an NSTextView because that is where our formatted text will appear.

To see the results of our formatting it will be useful to use NSTextView's ruler. To see the ruler it is necessary to add the Format menu to our menu bar. Therefore, before leaving IB, we drag the Format menu onto our project's main menu bar and give Show Ruler a key equivalent:


Figure 2. For convenience, in Interface Builder we drag a Format menu onto the menu bar and give Show Ruler a key equivalent.

The view

For our purposes, the important thing to know about NSTextView is that the text displayed in an NSTextView is its textStorage and that textStorage holds attributed strings. The textStorage is an instance of NSTextStorage which inherits from NSAttributedString itself. Attributed strings are Cocoa Foundation objects that contain both ordinary NSString's and formatting objects that apply to those strings, for example, NSFont and NSParagraphStyle. You can bypass dealing with NSTextView's textStorage directly, that is, you can [myNSTextView setString:@"aString"], but @"aString" will adopt either the default paragraph style or a previous style already residing in the textStorage.

Therefore, in order for text to appear formatted in an NSTextView we have to: 1) create an NSAttributedString instance initialized with the string we want to format, and 2) give that NSAttributedString instance the objects that it will use to format the string-in this case an NSParagraphStyle object. This attributed string goes into our NSTextView's textStorage where it appears formatted to the user.

The Controller

The interface buttons are connected to the controller's actions in a typical fashion. Basically, each button initiates a controller action to display a different formatted paragraph in the NSTextView. The controller does this task by sending a string (NSString) to the model object. The model object will return attributed strings (NSAttributedString's attributed with NSParagraphStyle's) to the controller. Finally, the controller will pass the attributed string to the text storage of the NSTextView where it will appear formatted to the user.

Here is one of the three controller actions:

applyStyle1

This method sets a pattern for the other two belonging to the controller. An unformatted string is 
put in the NSTextView for comparison purposes only. The program pauses so the user can see it. Next, 
the string is sent to the model object which returns it as an attributed string. Finally, the 
attributed string goes into the NSTextView revealing the new format. Refer to the source to see the 
other two action methods, applyStyle2 and applyStyle3. 

- (IBAction)applyStyle1:(id)sender
{
   MyModel *theModel;
   NSAttributedString *anAttString;
   NSString *aString;
   // a string containing multiple paragraphs
   aString = @"On a merry-go-round in the night, ";
   aString = [aString stringByAppendingString:
      @"Coriolis was shaken with fright.\n"];
   aString = [aString stringByAppendingString:
      @"Despite how he walked, "];
   aString = [aString stringByAppendingString:
      @"'Twas like he was stalked,\n"];
   aString = [aString stringByAppendingString:
      @"By some fiend always pushing him right."];
// limerick by David Morin, Eric Zaslow, E'beth Haley, John Golden, and Nathan Salwen,
//   http://www.aps.org/apsnews/11855.html
   // a convenience method to restore the default paragraph style to the NSTextView
   [self resetTextView]; 
   // install string w/o changing paragraph style for comparison
   [myNSTextView setString:aString]; 
   [myNSTextView display]; // force redraw
   sleep(1); // pause
   
   // now convert aString to an NSAttributedString by applying an NSParagraphStyle
   //   using the model object
   theModel = [[MyModel alloc]init];
   anAttString = [theModel attributeString1:aString];
   [theModel release];
   
   // now that we have the attributed string, put it into the NSTextView.
   // In order to get multiple attributed strings into a textStorage use
//      [myNSTextView insertText:attributedString] instead
   [[myNSTextView textStorage]
      setAttributedString:anAttString];
   [myNSTextView setNeedsDisplay:YES];
   return;
}

The Model

MyModel has a method for each of the controller's actions. It is here that we make use of NSParagraphStyle. Each method takes an ordinary NSString and returns it as an NSAttributedString so it can end up formatted in the NSTextView. When running the program, click inside the NSTextView and make the ruler visible. Some of the paragraph style attributes that we set show up on the NSTextView's ruler:


Figure 3. Many of NSParagraphStyle attributes appear in the NSTextView ruler.

Following are the methods used to create NSParagraphStyle's and apply them to strings thus creating NSAttributedString's:

attributeString1

This method creates an NSMutableAttributedString, using an NSString and an NSMutableParagraphStyle.

-(NSMutableAttributedString *) attributeString1:
      (NSString *) aString
{
   NSMutableParagraphStyle *aMutableParagraphStyle;
   NSMutableAttributedString   *attString;
   /*
   The only way to instantiate an NSMutableParagraphStyle is to mutably copy an
   NSParagraphStyle. And since we don't have an existing NSParagraphStyle available
   to copy, we use the default one.
   
   The default values supplied by the default NSParagraphStyle are:
      Alignment   NSNaturalTextAlignment
      Tab stops   12 left-aligned tabs, spaced by 28.0 points
      Line break mode   NSLineBreakByWordWrapping
      All others   0.0
   */
   aMutableParagraphStyle =
      [[NSParagraphStyle defaultParagraphStyle]mutableCopy];
   
   // Now adjust our NSMutableParagraphStyle formatting to be whatever we want.
   // The numeric values below are in points (72 points per inch)
   [aMutableParagraphStyle
      setAlignment:NSLeftTextAlignment];
   [aMutableParagraphStyle setLineSpacing:5.5];
   [aMutableParagraphStyle setParagraphSpacing:25.5];
   [aMutableParagraphStyle setHeadIndent:25.0];
   [aMutableParagraphStyle setTailIndent:-45.0];
   // setTailIndent: if negative, offset from right margin (right margin mark does
   //      NOT appear); if positive, offset from left margin (margin mark DOES appear)
   [aMutableParagraphStyle setFirstLineHeadIndent:65.0];
   [aMutableParagraphStyle
      setLineBreakMode:NSLineBreakByWordWrapping];
   /*
    possible allignments
      NSLeftTextAlignment
      NSRightTextAlignment
      NSCenterTextAlignment
      NSJustifiedTextAlignment
      NSNaturalTextAlignment
    possible line wraps
      NSLineBreakByWordWrapping
      NSLineBreakByCharWrapping
      NSLineBreakByClipping
    */
   
   // Instantiate the NSMutableAttributedString with the argument string
   attString = [[NSMutableAttributedString alloc]
      initWithString:aString];
   // Apply your paragraph style attribute over the entire string
   [attString addAttribute:NSParagraphStyleAttributeName
      value:aMutableParagraphStyle
      range:NSMakeRange(0,[aString length])];
   [aMutableParagraphStyle release]; // since it was copy'd
   [attString autorelease]; // since it was alloc'd
   return attString;
}

If your NSTextView already has attributed strings in its textStorage, you can get the NSParagraphStyle by:

aMutableParagraphStyle = [[myTextView typingAttributes]
   objectForKey:@"NSParagraphStyle"];

The NSParagraphStyle returned above comes from the attributes of the text from where the cursor is found inside the NSTextView. NSParagraphStyle's can span multiple paragraphs but there cannot be more than one per paragraph.

attributeString2

This method creates an array of NSTextTab's and applies them to the NSMutableParagraphStyle before 
it is used to create the NSMutableAttributedString.

-(NSMutableAttributedString *)
   attributeString2:(NSString *) aString
{
   float firstColumnInch = 1.75,
      otherColumnInch = 0.6, pntPerInch = 72.0;
   int i;
   NSTextTab *aTab;
   NSMutableArray *myArrayOfTabs;
   NSMutableParagraphStyle *aMutableParagraphStyle;
   NSMutableAttributedString   *attString;
   myArrayOfTabs = [NSMutableArray arrayWithCapacity:14];
   aTab = [[NSTextTab alloc]
      initWithType:NSLeftTabStopType
      location:firstColumnInch*pntPerInch];
   [myArrayOfTabs addObject:aTab];
   [aTab release]; // aTab was alloc'd and the array owns it now so release it
   for(i=1;i<14;i++)
   {
      aTab = [[NSTextTab alloc]
         initWithType:NSRightTabStopType
         location:(firstColumnInch*pntPerInch)
         + ((float)i * otherColumnInch * pntPerInch)];
      [myArrayOfTabs addObject:aTab];
[aTab release]; // aTab was alloc'd and the array owns it now so release it
   }
   /*
   possible tab stop types
      NSLeftTabStopType
      NSRightTabStopType
      NSCenterTabStopType
      NSDecimalTabStopType
    */
    
   aMutableParagraphStyle =
      [[NSParagraphStyle defaultParagraphStyle]mutableCopy];
   [aMutableParagraphStyle setTabStops:myArrayOfTabs];
   attString = [[NSMutableAttributedString alloc]
      initWithString:aString];
   [attString addAttribute:NSParagraphStyleAttributeName
      value:aMutableParagraphStyle
      range:NSMakeRange(0,[aString length])];
   [aMutableParagraphStyle release];
   [attString autorelease];
   return attString;
}

Tabbed text appears as below without using NSParagraphStyle:


Figure 4. Default behavior of an NSTextView containing tabbed text. The tab spacing is arbitrary and the lines wrap even though there is space enough to hold the whole line.

Tabbed text appears as below after creating an NSMutableParagraphStyle and assigning it to an NSMutableAttributedString using the attributeString2 method:


Figure 5. By using an NSMutableParagraphStyle the tab stops have been precisely set and the lines do not wrap unexpectedly.

attributeString3

This method supplies a way to parse a string containing multiple paragraphs and apply different 
paragraph styles to each.

-(NSMutableArray *) attributeString3:(NSString *)aString 
{
   NSRange myRange,rangeOfLine,rangeOfLineContent;
   unsigned startIndex,lineEndIndex,contentsEndIndex;
   NSMutableParagraphStyle
      *aMutableParagraphStyle1,*aMutableParagraphStyle2;
   NSMutableAttributedString   *attString;
   int lineCtr;
   NSMutableArray * arrayOfNSMutableAttributedString;
   NSString *pulledOutParagraph;
   arrayOfNSMutableAttributedString
      = [NSMutableArray arrayWithCapacity:5];
   /*
    lines can be terminated in the following ways for use with
      getLineStart:end:contentsEnd:forRange:
    *    U+000D (\r or CR), Mac
    *    U+2028 (Unicode line separator)
    *    U+000A (\n or LF), Unix
    *    U+2029 (Unicode paragraph separator)
    *    \r\n, in that order (also known as CRLF), Windows
    */
   /*
   Using getLineStart:end:contentsEnd:forRange: 
   @"Big\r\nMac    --example string
   in this case
      1st contentsEndIndex    is set to 3,
         the first character past the line content,
         line content being defined as the characters not including
         line termination character(s)
      1st lineEndIndex    is set to 5
         the first character past the end of line character(s)
   */
   // make 2 different paragraph styles
   aMutableParagraphStyle1 =
      [[NSParagraphStyle defaultParagraphStyle]mutableCopy];
   aMutableParagraphStyle2 =
      [[NSParagraphStyle defaultParagraphStyle]mutableCopy];
   [aMutableParagraphStyle1
      setAlignment:NSLeftTextAlignment];
   [aMutableParagraphStyle2
      setAlignment:NSRightTextAlignment];
   
   // initialize
   myRange = NSMakeRange(0,0); // (location,length)
   lineEndIndex = 0;
   lineCtr = 0;
   /*
    The while() block below walks down the string pulling out lines (paragraphs)
   including their end of line (paragraph) characters, converts them to attributed strings,
   and adds them to an array.
   The range in the getLineStart:end:contentsEnd:forRange: method has to be picky
   about where it's location is but doesn't have to be picky about length (i.e. 0 will do)
   */
   while(lineEndIndex < [aString length])
   {
      [aString getLineStart: &startIndex
         end: &lineEndIndex
         contentsEnd: &contentsEndIndex
         forRange: myRange];
      // rangeOfLineContent excludes line termination character(s)
      rangeOfLineContent =
         NSMakeRange(startIndex,contentsEndIndex-startIndex); 
      // rangeOfLine includes line termination character(s)
      rangeOfLine =
         NSMakeRange(startIndex,lineEndIndex-startIndex); 
      // apply paragraph style to pulledOutParagraph
      pulledOutParagraph =
         [aString substringWithRange:rangeOfLine];
      attString = [[NSMutableAttributedString alloc]
         initWithString:pulledOutParagraph];
      if(lineCtr % 2 == 0) // alternate paragraph styles on odd/even lines
      {
         // If range.length below is zero then the paragraph style is not applied.
         //   For strings with length > 0, range.length should be > 0 and <= length of the
         //   string so NSMakeRange(0,1) would work as well below
         //   provided you don't have an empty string.
         [attString addAttribute:NSParagraphStyleAttributeName
            value: aMutableParagraphStyle1
            range: NSMakeRange(0,[pulledOutParagraph length])];
      }
      else
      {
         [attString addAttribute:NSParagraphStyleAttributeName
            value:aMutableParagraphStyle2
            range:NSMakeRange(0,[pulledOutParagraph length])];
      }
      [arrayOfNSMutableAttributedString addObject:attString];
      [attString release]; // the array now owns it
      lineCtr++;
      // recalculate the range before looping
      myRange = NSMakeRange(lineEndIndex,0); 
   }
   [aMutableParagraphStyle1 release];
   [aMutableParagraphStyle2 release];
   return arrayOfNSMutableAttributedString;
}

Conclusion

Cocoa's text system is extensive involving many classes not even mentioned here. But if you just need to get some formatted, tabbed text into an NSTextView for that special report, the methods explained here should do the trick.


Clark Jackson test drove the first Mac and recognized that it was about to change the world. Lately he has been busy wearing many hats automating energy accounting in the rapidly changing electrical power industry at Tacoma Power. He can be contacted at cjackson@cityoftacoma.org.

 
AAPL
$102.50
Apple Inc.
+0.25
MSFT
$45.43
Microsoft Corpora
+0.55
GOOG
$571.60
Google Inc.
+2.40

MacTech Search:
Community Search:

Software Updates via MacUpdate

Skype 6.19.0.450 - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
VueScan 9.4.41 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Cloud 3.0.0 - File sharing from your men...
Cloud is simple file sharing for the Mac. Drag a file from your Mac to the CloudApp icon in the menubar and we take care of the rest. A link to the file will automatically be copied to your clipboard... Read more
LibreOffice 4.3.1.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
SlingPlayer Plugin 3.3.20.505 - Browser...
SlingPlayer is the screen interface software that works hand-in-hand with the hardware inside the Slingbox to make your TV viewing experience just like that at home. It features an array of... Read more
Get Lyrical 3.8 - Auto-magically adds ly...
Get Lyrical auto-magically add lyrics to songs in iTunes. You can choose either a selection of tracks, or the current track. Or turn on "Active Tagging" to get lyrics for songs as you play them.... Read more
Viber 4.2.2 - Send messages and make cal...
Viber lets you send free messages and make free calls to other Viber users, on any device and network, in any country! Viber syncs your contacts, messages and call history with your mobile device,... Read more
Cocktail 7.6 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
LaunchBar 6.1 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more

Latest Forum Discussions

See All

Rhonna Designs Magic (Photography)
Rhonna Designs Magic 1.0 Device: iOS Universal Category: Photography Price: $1.99, Version: 1.0 (iTunes) Description: Want to sprinkle *magic* on your photos? With RD Magic, you can add colors, filters, light leaks, bokeh, edges,... | Read more »
This Week at 148Apps: August 25-29, 2014
Shiny Happy App Reviews   | Read more »
Qube Kingdom – Tips, Tricks, Strategies,...
Qube Kingdom is a tower defense game from DeNA. You rally your troops – magicians, archers, knights, barbarians, and others – and fight against an evil menace looking to dominate your kingdom of tiny squares. Planning a war isn’t easy, so here are a... | Read more »
Qube Kingdom Review
Qube Kingdom Review By Nadia Oxford on August 29th, 2014 Our Rating: :: KIND OF A SQUARE KINGDOMUniversal App - Designed for iPhone and iPad Qube Kingdom has cute visuals, but it’s a pretty basic tower defense game at heart.   | Read more »
Fire in the Hole Review
Fire in the Hole Review By Rob Thomas on August 29th, 2014 Our Rating: :: WALK THE PLANKUniversal App - Designed for iPhone and iPad Seafoam’s Fire in the Hole looks like a bright, 8-bit throwback, but there’s not enough booty to... | Read more »
Alien Creeps TD is Now Available Worldwi...
Alien Creeps TD is Now Available Worldwide Posted by Ellis Spice on August 29th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Dodo Master Review
Dodo Master Review By Jordan Minor on August 29th, 2014 Our Rating: :: NEST EGGiPad Only App - Designed for the iPad Dodo Master is tough but fair, and that’s what makes it a joy to play.   | Read more »
Motorsport Manager Review
Motorsport Manager Review By Lee Hamlet on August 29th, 2014 Our Rating: :: MARVELOUS MANAGEMENTUniversal App - Designed for iPhone and iPad Despite its depth and sense of tactical freedom, Motorsport Manager is one of the most... | Read more »
Motorsport Manager – Beginner Tips, Tric...
The world of Motorsport management can be an unforgiving and merciless one, so to help with some of the stress that comes with running a successful race team, here are a few hints and tips to leave your opponents in the dust. | Read more »
CalPal Update Brings the App to 2.0, Add...
CalPal Update Brings the App to 2.0, Adds Lots of New Stuff Posted by Ellis Spice on August 29th, 2014 [ permalink ] | Read more »

Price Scanner via MacPrices.net

Apple now offering refurbished 21-inch 1.4GHz...
The Apple Store is now offering Apple Certified Refurbished 21″ 1.4GHz iMacs for $929 including free shipping plus Apple’s standard one-year warranty. Their price is $170 off the cost of new models,... Read more
Save $50 on the 2.5GHz Mac mini, on sale for...
B&H Photo has the 2.5GHz Mac mini on sale for $549.99 including free shipping. That’s $50 off MSRP, and B&H will also include a free copy of Parallels Desktop software. NY sales tax only. Read more
Save up to $300 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $300 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
The Rise of Phablets
Carlisle & Gallagher Consulting Group, a businesses and technology consulting firm focused solely on the financial services industry, has released an infographic depicting the convergence of... Read more
Bad Driver Database App Allows Good Drivers t...
Bad Driver Database 1.4 by Facile Group is a new iOS and Android app that lets users instantly input and see how many times a careless, reckless or just plain stupid driver has been added to the... Read more
Eddy – Cloud Music Player for iPhone/iPad Fre...
Ukraine based CapableBits announces the release of Eddy, its tiny, but smart and powerful cloud music player for iPhone and iPad that allows users to stream or download music directly from cloud... Read more
A&D Medical Launches Its WellnessConnecte...
For consumers and the healthcare providers and loved ones who care for them, A&D Medical, a leader in connected health and biometric measurement devices and services, has launched its... Read more
Anand Lal Shimpi Retires From AnandTech
Anand Lal Shimpi, whose AnandTech Website is famous for its meticulously detailed and thoroughgoing reviews and analysis, is packing it in. Lal Shimpi, who founded the tech site at age 14 in 1997,... Read more
2.5GHz Mac mini, Apple refurbished, in stock...
The Apple Store has Apple Certified Refurbished 2.5GHz Mac minis available for $509, $90 off MSRP. Apple’s one-year warranty is included, and shipping is free. Read more
13-inch 2.5GHz MacBook Pro on sale for $999,...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999.99 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.