Home > Articles > Mobile Application Development & Programming

This chapter is from the book


It is easy to confuse “glyphs” with “characters” because it is the glyph of the character that is drawn onscreen and hence what we are looking at. A glyph is a pattern, a shape, or an outline of the character’s image. Characters are what you type; glyphs are what you see.

Two points need to be called out:

  • A character conveys differences in meaning or sound. No appearance property is associated with it.
  • A glyph conveys differences in appearance. The key thing is appearance. A glyph has no intrinsic meaning.

Figure 2.4 shows a sampling of some glyphs for the Latin character “c.” Note that they are all of the same character, lowercase “c,” and therefore have the same meaning, but they are displayed, shaped, and outlined differently.

Figure 2.4

Figure 2.4 A sampling of glyphs for the lowercase character “c.”

There are also cases in which a character will have a glyph assigned to it based on the font set so that the shape it displays is nothing like the traditional shape of the character. “Wingdings” and assorted symbol fonts like that are prime examples in which the lowercase “c” character actually displays as 067fig01.jpg.

Also, variations in a character’s glyph can be associated with things like cursive connectors. In this scenario, the character is displayed traditionally, but it has slight changes depending on what character precedes it and what character follows it. Again, no meaning is lost; we have just gained flourishes.

Contextual Glyphs

For the Arabic and Indic family of languages, a character’s glyph can change greatly depending on the glyph’s position within the word and can change depending on characters that follow and precede it. Let’s focus on the Arabic character “Ain,” "067fig02.jpg" (Unicode code point U+0639). Figure 2.5 displays the different glyphs used for “Ain” depending on its context and position.

Figure 2.5

Figure 2.5 Examples of contextual glyphs.

Arabic is a right-to-left language, so the first/initial character is the rightmost, the second is to the left of that, the third is to the left of the second, and so on.

Another example is the Greek character sigma (σ). When it is used at the end of a word and the characters of that word are not all uppercase, the final form of the character “ς” is used, for example, “068fig01.jpg” (Odysseus). Note the two sigmas in the center of the name that remain the same and the word-final sigma at the end. Same character, different glyphs. This example also demonstrates that uppercase and lowercase are handled as separate characters and not as the same character—same character value, only displayed differently.

Now that we’ve covered glyphs, let’s move on to fonts.


The term font is a common, everyday household term. We generally think of it as the shape and display of the characters we are working with, as well as the size and spacing. It is a combination of these properties, as well as the typeface associated with the font.

Font files are your storage depot for the glyphs that are associated with the characters. Well-crafted fonts won’t fake bold, italic, and bold-italic variations but have built-in, designed glyphs for these variations. After your application has worked out what characters it is dealing with, it will look in the font for glyphs in order to display or print those characters. Of course, if the encoding information was wrong, it will be looking up glyphs for the wrong characters.

A given font will usually cover a single character set. In the case of a large character set, like Unicode, just a subset of all the available characters will be available. This is one of the many reasons you will see specific fonts for CJK characters. It is more practical to have specific fonts hold specific character sets for both performance and file-size benefits.

If your font doesn’t have a glyph for a particular character, some applications as well as the OS will look for the missing glyph in other fonts on your system. Although this eliminates a missing glyph from displaying as an empty box or a box containing a question mark, it does have the potential of having the glyph look different from the surrounding text, like a ransom note.


The term ligature, which simply means “connection,” originates from the Latin ligari. The term itself doesn’t imply a certain purpose or use. Today, there are two possible ways to define a ligature, and both ways can appear in connection or individually. If we talk about the display of characters, a ligature is made from two or more letters, which appear connected. In handwriting such connections are created all the time, especially with cursive print.

Some ligatures are two separate characters displayed with a connected glyph, whereas the glyph is one character with its own code point.

Standard ligatures include might include fi, fl, ff, ffi, ffl, and ft. The purpose of these ligatures is to make certain letter parts that tend to knock up against each other more attractive.

Here are some individual Unicode ligature characters:

  • æ—CYRILLIC SMALL LIGATURE A IE; Unicode: U+04D5; UTF-8: D3 95
  • fl—LATIN SMALL LIGATURE FL; Unicode: U+FB02; UTF-8: EF AC 82
  • fi—LATIN SMALL LIGATURE FI; Unicode: U+FB01; UTF-8: EF AC 81

Code Snippet to Compare Ligatures

Listing 2.7 compares the single-character ligature “ff” to the two-character equivalent “ff.” The localizedCompare method returns an NSComparisonResult value, which could be an enum of NSOrderedAscending, NSOrderedSame, or NSOrderedDescending.

Listing 2.7 Using Localized Compare to Determine Whether Characters Are Equal

NSString *characters = @"ff"; // Two "f" characters
NSString *ligature = @"\uFB00"; // Single character - "ff" ligature
NSComparisonResult result = [characters localizedCompare: ligature];
if (result == NSOrderedSame){
    NSLog(@"%@ is equal to %@", characters, ligature);
} else{
    NSLog(@"Characters are not equal.");

The code returns “ff is equal to ff.”

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020