TweetFollow Us on Twitter

Spaced Out

Volume Number: 18 (2002)
Issue Number: 12
Column Tag: Mac OS X

Spaced Out

Adding Paragraph Spacing to the Cocoa Text System

by Andrew C. Stone

One of my favorite Cocoa demos is to make a full featured word processor application in 5 minutes - complete with rulers, tabs, embedded graphics, line spacing, kerning, ligatures, baseline, colors, multi-font, automatic spell checking and more - (see Cocoa's powerful text system is a collection of classes that can meet almost any text need, and I highly recommend reading the documentation for these classes:,NSText and NSTextView (the display classes), NSTextStorage and NSAttributedString (how rich strings store all the attributes of unicode text), NSLayoutManager (manages an NSTextStorage and set of NSTextContainers which display in an NSTextView) and playing with the sample Text layout application available in the Developer distribution in /Developer/Examples/AppKit/TextSizingExample.

These full featured classes are getting more powerful with each major system release. In Mac OS X 10.2, a feature which was previously defined in the API was implemented in NSParagraphStyle:


- (float)paragraphSpacing

Returns the space added at the end of the paragraph to separate it from the following paragraph. This value is always nonnegative.

See Also: - lineSpacing - setParagraphSpacing: (NSMutableParagraphStyle)

Paragraph spacing is the additional distance between paragraphs (that is, whenever a <RETURN> appears in the text). This amount is in points (72 per inch) and by default is 0. It's added to any additional line spacing that applies to that paragraph style.

But, although the implementation is there, the interface is not. The ruler, which comes for free with NXTextView, and which contains controls for alignment, line spacing, and tabs, currently lacks any control for setting the paragraph spacing. This article will show you how to add a custom control to the standard text system ruler.

Figure 1: The standard text ruler in Mac OS X 10.2 doesn't have a paragraph spacing control.

Just using simple subclasses of NSTextView and NSLayoutManager, our page layout and web authoring application Create(R) can flow text through any size containers, place rich text along any path, apply neon and custom pattern effects to any text, and place text outside or inside of any path. Once Jaguar shipped, we could easily add paragraph spacing to our text - if we could figure out a way to add a new control to the ruler that automatically attaches itself to any NSTextView in an NSScrollView.

Like everything with Cocoa - if it's hard it's wrong. So finding an easy solution with modular application is the always the goal of any Cocoa programming challenge.

Our design imperatives include:

  • make it simple

  • make it small so it doesn't get in the way

  • make it a modular nib file

The solution has 3 parts - a user interface built in InterfaceBuilder, the create/update code in an NSLayoutManager subclass, and code in an NSTextView subclass which actually sets the spacing and maintains the undo stack.

So, I chose to make the narrowest UI possible - using the P symbol for paragraph and an NSStepper:

Figure 2: Create(R) adds a paragraph spacer next to the line spacing tools - P

The first problem is how do we get at the ruler to install the new device? It's owned by NSLayoutManager, which provides a method that returns this ruler view - so that seems like the most appropriate place to instantiate and update our own user interface addition which can set the paragraph spacing:

- (NSView *)rulerAccessoryViewForTextView:(NSTextView *)aTextView 
paragraphStyle:(NSParagraphStyle *)paraStyle ruler:(NSRulerView *)aRulerView enabled:(BOOL)flag

Returns the accessory NSView for aRulerView. This accessory contains tab wells, text alignment buttons, and so on. paraStyle is used to set the state of the controls in the accessory NSView; it must not be nil. If flag is YES the accessory view is enabled and accepts mouse and keyboard events; if NO it's disabled.

This method is invoked automatically by the NSTextView object using the layout manager. You should rarely need to invoke it, but you can override it to customize ruler support.

Let's Just Face it

We'll use InterfaceBuilder to create the interface and even the stub files for our new class, ParagraphSpacer:

    1. Launch Interface Builder

    2. File -> New..., Cocoa, "Empty", Click "New"

    3. Save this as "ParagraphSpacer.nib" in your project directory - also add it to your project when asked.

    4. Double-click the "File's Owner" icon in the folio window - NSObject will be selected in the Classes tab

    5. Control-Click NSObject and select "Create Subclass" - name it "ParagraphSpacer"

    6. Add two outlets: stepper and containerView by Control-Clicking ParagraphSpacer and choose "Add Outlet to ParagraphSpacer".

    7. Control-click ParagraphSpacer and choose "Create Files for Paragraph Spacer" - add these to your project

    8. Choose "Instances" tab, select "File's Owner", Info-> Custom Class, select "ParagraphSpacer"

    9. From the Tab icon on the Palette, drag a "Custom View" into the folio window

    10. Set the view's size with , Info -> Size, 26 wide by 28 tall

    11. Drag in "System Font Text", select all, delete, type P, Info -> Size 10 wide by 17 tall, locate on left

    12. Drag in an NSStepper from Slider Icon tab on Palette, adjust location as needed

    13. Connect the File's owner to the two instance variables - the stepper, and the view which holds the stepper and the static P text.

    14. Save ParagraphSpacer.nib


A very simple class which just returns its two instance variables.We need these to install the view into the Ruler view hierarchy and set the value of the stepper during updates:

/* ParagraphSpacer */
#import <Cocoa/Cocoa.h>
@interface ParagraphSpacer : NSObject
    IBOutlet id containerView;
    IBOutlet NSStepper *stepper;
- (NSStepper *)stepper;
- (NSView *)containerView;
#import "ParagraphSpacer.h"
@implementation ParagraphSpacer
- (id) init {
    self = [super init];
    if (![NSBundle loadNibNamed:@"ParagraphSpacer.nib" owner:self])
   NSLog(@"couldn't load ParagraphSpacer\n");
    return self;
- (NSStepper *)stepper; {
    return stepper;
- (NSView *)containerView; {
    return containerView;


We just need to add one method to our NSLayoutManager subclass. Note that we call [super rulerAccessoryViewForTextView: ... ] to get the standard ruler provided for us, then we check to see if we have already initialized the paragraph spacer, and if not, proceed to create it, find it's proper position in the ruler and install it. We'll travel down the view hierarchy, looking at the subviews of each view. When we find a view with several subviews, then we know we're in the right place. When we find the view that starts far to the left, ie, not the tab well, but the NSBox which surrounds the alignment and line spacing controls, we'll place our control right next to it. We just have to hope that the ruler doesn't change drastically - if it does, it will probably have more controls in it, and our layout may be wrong.

Each time this method gets called, we'll set the target of the stepper to be the current text view with an action of changeParagraphSpacing:, and update the value of the stepper so that it sends the target the right value when incrementing or decrementing.

@interface SDLayoutManager : NSLayoutManager
    NSStepper *_paragraphStepper;
@implementation SDLayoutManager
- (NSView *)rulerAccessoryViewForTextView:(NSTextView *)view paragraphStyle:(NSParagraphStyle *)style 
ruler:(NSRulerView *)ruler enabled:(BOOL)isEnabled {

    NSView *accessory = [super rulerAccessoryViewForTextView:view paragraphStyle:style ruler:ruler 
    if (!_paragraphStepper) {
        ParagraphSpacer *spacer = [[ParagraphSpacer allocWithZone:[self zone]] init];
        NSView *viewToAdd = [spacer containerView];
        NSArray *subviews = [accessory subviews];
        NSView *viewToAddTo = accessory;
        unsigned int i, count = [subviews count];
        NSRect viewRect = [viewToAdd bounds];
        if (count == 1) {
            viewToAddTo = [subviews objectAtIndex:0];
            subviews = [[subviews objectAtIndex:0] subviews];
            count = [subviews count];
        _paragraphStepper = [spacer stepper];
        for (i = 0; i < count; i++) {
            NSView *v = [subviews objectAtIndex:i];
            NSRect r = [v frame];
            if (r.origin.x < 10.0) {   // it's the box containing the left controls)
                viewRect.origin.x = r.origin.x + r.size.width;
                viewRect.origin.y = 0.0;
                [viewToAdd setFrame:viewRect];
                [viewToAddTo addSubview:viewToAdd];
    [_paragraphStepper setDoubleValue:style? [style paragraphSpacing] : 0.0];
    [_paragraphStepper setTarget:view];
    [_paragraphStepper setAction:@selector(changeParagraphSpacing:)];
    return accessory;


If you don't want to subclass NSTextView, you could instead add the changeParagraphSpacing: method to a category of NSTextView. This is not the case with the NSLayoutManager subclass, because we need to call super's implementation of rulerAccessoryViewForTextView:paragraphStyle:ruler:enabled:.

The main reason we place this code in NSTextView or a subclass is so we get the free automatic undo associated with Text. To do that, we alert the text system that there will be changes in a certain range with shouldChangeTextInRange: replacementString: with a replacement string of "nil" , which means other attributes are changing, but not any characters. Then, we walk over text paragraph style by paragraph style, setting the paragraph spacing to the value determined by the stepper (up or down a point from the first style in the selection). Note that if there are no paragraph attributes, one is added.

Finally, we alert the text that we are done changing it with didChangeText, and we add a custom action name so the menu will say "Undo Paragraph Spacing" and "Redo Paragraph Spacing".

@interface SDTextView: NSTextView
@implementation SDTextView
- (void)changeParagraphSpacing:(id)sender {
    double value = [sender doubleValue];
    NSRange range = [self rangeForUserParagraphAttributeChange];
    if (range.length > 0) {
        NSRange remainingRange = range;
        NSTextStorage *storage = [self textStorage];
        [self shouldChangeTextInRange:range replacementString:nil];
        while (remainingRange.length > 0) {
                NSRange effectiveRange;
                NSParagraphStyle *para = [storage attribute:NSParagraphStyleAttributeName 
                atIndex:remainingRange.location longestEffectiveRange:&effectiveRange 
                if (para == nil) {
                    para = [[[NSMutableParagraphStyle alloc] init] autorelease];
                    [para setParagraphStyle:[NSParagraphStyle defaultParagraphStyle]];
                } else para = [[para mutableCopyWithZone:[self zone]]autorelease];
                [para setParagraphSpacing:value];
                [storage addAttribute:NSParagraphStyleAttributeName value:para range:remainingRange];
                if (NSMaxRange(effectiveRange) < NSMaxRange(remainingRange)) {
                    remainingRange.length = NSMaxRange(remainingRange) - NSMaxRange(effectiveRange);
                    remainingRange.location = NSMaxRange(effectiveRange);
                } else {
            [self didChangeText];
            [[self undoManager] setActionName:NSLocalizedStringFromTable(@"Paragraph Spacing",
            @"Muktinath",@"change of space between paragraphs")];

All Together Now

Your final task is just to be sure you create your text system with the special SDLayoutManager. If you have a shared text editor, it might look something like this:

static NSTextView *newEditor(TextArea *self) {
    SDTextView *tv;
    NSTextContainer *tc;
    // This method returns an NSTextView whose SDLayoutManager has a refcount of 1.  It is 
    the caller's responsibility to release the SDLayoutManager.  This function is only for the use of
    the following method.
    SDLayoutManager *lm = [[SDLayoutManager allocWithZone:NULL] init];
    tv = [[SDTextView allocWithZone:NULL] initWithFrame:NSMakeRect(0.0, 0.0, 100.0, 100.0) 
    tc = [[NSTextContainer allocWithZone:NULL] initWithContainerSize:NSMakeSize(1.0e6, 1.0e6)];
    [lm addTextContainer:tc];
    [tc release];
    [tc setTextView:tv];
    [tv release];
    return tv;

Figure 3: The new text ruler with paragraph spacing stepper installed.


The Cocoa text system just keeps getting better. And sometimes there are features that are still hidden from the user interface, such as paragraph spacing in Jaguar 10.2. With a little Cocoa magic, it's easy to install your own custom controls and add more functionality to the standard text object.

Andrew Stone, CEO of Stone Design,, has been the principal architect of several solar houses and over a dozen Cocoa applications shipping for Mac OS X.


Community Search:
MacTech Search:

Software Updates via MacUpdate

Facility 47 (Games)
Facility 47 1.0.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.1 (iTunes) Description: You wake up alone and freezing in an icy cell. You try the cell door but it’s locked, it seems that you are stuck with no... | Read more »
The Walking Dead: No Man’s Land guide -...
A new update for The Walking Dead: No Man’s Land was released last week, making it the perfect time for you to head back to your base and take out some walkers. Here’s the lowdown on what’s new to the game, and how to take advantage. [Read more] | Read more »
Goat Rider guide - Tips and tricks to st...
We've all been there. One second, we're riding high on a crazed goat, and the next, we've been tossed off it like someone who's no good at goat ridin'. [Read more] | Read more »
Real Boxing 2 CREED: How to become a gre...
Just in time for Rocky fans who can’t wait to see CREED, the latest movie, we have the official tie-in game,Real Boxing 2 CREED. It builds on the success of its predecessor and there’s lots to take in so we at 148apps thought we’d run you through... | Read more »
CoinOp Heroes 2 guide - How to build an...
CoinOp Heroes 2 justlaunched and, like all clickers, it's dangerously addictive stuff. You have to furiously tap your screen to defeat wave after wave of foes and earn an insane amount of cash to spend on character upgrades and an army of minions... | Read more »
Dr. Panda Firefighters (Education)
Dr. Panda Firefighters 1.0.1 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0.1 (iTunes) Description: FIGHT FIRES AND SAVE THE DAY!Work together with Dr. Panda and his firefighting team to rescue his trapped... | Read more »
Puddle + (Games)
Puddle + 1.0 Device: iOS iPhone Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Puddle is back in a new "+" edition featuring enhanced graphics, new videos and Apple TV support ! No IAP and No Ads. Dive into Puddle... | Read more »
Football Manager Mobile 2016 (Games)
Football Manager Mobile 2016 7.0.0 Device: iOS Universal Category: Games Price: $8.99, Version: 7.0.0 (iTunes) Description: Football Manager Mobile 2016 is designed to be played on the move and is the quickest way to manage your... | Read more »
Kill Shot Bravo guide - How to become an...
Kill Shot Bravo is a disturbing amount of fun. No matter how many times I play a game that encourages me to snipe people in the head, I feel a little uneasy at how satisfying it is. Here are some useful tips to get you started on your path to... | Read more »
The best note-taking app on iPhone and i...
Word processors are handy and all, but sometimes you just want to make a quick note. Whether it's to jot down your shopping list, some quick song lyrics, or a phone number, the ease of use of a note-taking app easily surpasses that of a heftier... | Read more »

Price Scanner via

Al Jazeera Launches New iOS And Android Mobil...
Doha, Qatar based Al Jazeera has launched new mobile and tablet apps on the iOS and Android systems bringing the latest Al Jazeera news and programmes live together with on-demand personalisation.... Read more
B&H Photo Holiday Sale: Up to $250 off Ma...
B&H Photo has all new Macs on sale for up to $500 off MSRP as part of their Holiday sale including free shipping plus NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off - 15″ 2.... Read more
Free Aura ‘Ultimate’ Mac App For Gmail Update...
Miami, Florida based Crosscoded has announced Aura 1.2.0, an update to the Mac app for Gmail. Aura mixes the power of a native client with the flexibility of the Gmail web app with support for up to... Read more
Apple Will Edge Closer to Samsung in Smartpho...
Total smartphone shipments for 2015 are projected to decline by 9.7% to 1.286 billion units, according to the latest report from global market research firm TrendForce. Though Chinese vendors have... Read more
12-inch MacBooks in stock for up to $120 off,...
Adorama has 12″ Retina MacBooks in stock for up to $120 off MSRP including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB Adapter,... Read more
Save 15% with Apple refurbished Mac Pros
The Apple Store has Apple Certified Refurbished Mac Pros available for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more
iPod touch (6th Gen) on sale for $40-$60 off...
Save $40 to $60 on a 6th generation iPod touch at Target with free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary: - 16GB iPod touch... Read more
13-inch 1.6GHz MacBook Air on sale for $849,...
Best Buy has the 2015 13″ 1.6GHz/128GB MacBook Air on sale for $849.99 on their online store. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-... Read more
Apple refurbished 15-inch 2.2GHz Retina MacBo...
Apple has Certified Refurbished 2014 15″ 2.2GHz Retina MacBook Pros available for $1609, $390 off original MSRP. Apple’s one-year warranty is included, and shipping is free. Read more
Weekend sale: 13-inch Retina MacBook Pros for...
Save up to $100 on the purchase of a new 2015 13″ Retina MacBook Pro at the following resellers. Shipping is free with each model: 2.7GHz/128GB MSRP $1299 2.7GHz/256GB... 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
Senior Business Development Manager, - *Appl...
# Senior Business Development Manager, - Apple Pay Job Number: 44473850 Santa Clara Valley, Califo ia, United States Posted: Nov. 20, 2015 Weekly Hours: **Job Summary** Read more
Content Producer, *Apple* University - Appl...
# Content Producer, Apple University Job Number: 44135153 Santa Clara Valley, Califo ia, United States Posted: Nov. 20, 2015 Weekly Hours: 40.00 **Job Summary** The Read more
*Apple* Media QA Manager - Apple (United Sta...
# Apple Media QA Manager Job Number: 44409763 Santa Clara Valley, Califo ia, United States Posted: Nov. 17, 2015 Weekly Hours: 40.00 **Job Summary** Apple Media Inte 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.