3. Advance Text Rendering In iOS
Topics covered in the presentation
• Back Ground
• Core Text
• How to Do It?
• How to Fix IT
or
Sohail Mohabbat Ali | iOS Mentor
4. Advance text Rendering in iOS
Text Rendering in iOS
• UIKit
• Core Graphics/Quartz
• Core Text
Sohail Mohabbat Ali | iOS Mentor
5. Advance text Rendering in iOS
Text Rendering in iOS Cont..
UIKit:
In UIKit you have and you add a word or a text line on
the screen by simple Drag-and-Drop in IB, but you cannot do
many things like strikethrough and custom formatting.
Sohail Mohabbat Ali | iOS Mentor
6. Advance text Rendering in iOS
Text Rendering in iOS Cont..
Core Graphics/Quartz:
In you can do pretty much everything the
system is capable of, but you need to calculate the position of each
glyph in your text and draw it on the screen.
Sohail Mohabbat Ali | iOS Mentor
7. Advance text Rendering in iOS
Text Rendering in iOS Cont..
Core Text:
lies right between the two! You have complete control over
position, layout, attributes like color and size, but Core Text takes care
of everything else for you – from word wrap to font rendering and more.
Sohail Mohabbat Ali | iOS Mentor
8. Advance text Rendering in iOS
Back Ground
A tale of two Apples
• The original Apple development team created “Classic” APIs
and
• The NeXT team created NS* APIs which we later called
“ ”
• Since the merge of the two company, solutions like
and were created to close the gap
• For modern, Unicode-aware text layout, there is which
is still a popular choice for now
Sohail Mohabbat Ali | iOS Mentor
9. Advance text Rendering in iOS
Background
More about ATSUI
• Short for “ ”
Like API (OSErr, Fixed, Pascal String, etc.)
• Fast, robust, powerful, but the API is bit complicate to use
(for font enumeration and selection) still exists, but ATSUI
is now , no 64-bit support
Sohail Mohabbat Ali | iOS Mentor
10. Advance text Rendering in iOS
Why Core Text ?
• Simpler, Core Foundation style API, much easier to call from
Cocoa apps
• Minimize between different data formats, improve
performance (up to 2 times faster according to Apple)
• Supported behavior (like font traits) closely matches with
Cocoa Text System
Sohail Mohabbat Ali | iOS Mentor
11. Advance text Rendering in iOS
What is easy with Core Text
• Lay formatted text down on the screen
• Fine tune the text’s appearance
• Add images inside the text content
• Display data in columns
• Display text with different transformations
Sohail Mohabbat Ali | iOS Mentor
12. Advance text Rendering in iOS
How to do it ?
Step 1: Prepare Attributed String
• First, you prepare a with all the parameters set
(to the whole string or part of the string):
NSAttributedString * str = [[NSAttributedString alloc]
initWithString:@”Hello core text world!”
attributes:[NSDictionary
dictionaryWithObjectsAndKeys:
[UIFont fontWithName:@"Helvetive" size:12.0],
(NSString *) kCTFontAttributeName]];
CFAttributedStringRef attrString =
(CFAttributedStringRef) str;
Sohail Mohabbat Ali | iOS Mentor
13. Advance text Rendering in iOS
What is easy with Core Text
Step 2: Create a CTFramesetter
• Now you can create a central object for Core Text typesetting:
, you will use it through the entire layout
process:
CTFramesetterRef framesetter =
CTFramesetterCreateWithAttributedString(attrString);
Sohail Mohabbat Ali | iOS Mentor
14. Advance text Rendering in iOS
What is easy with Core Text
Step 3: Create a CGPath
• Third, you add one or more (or other shapes) to form
a complete :
CGMutablePathRef path =
CGPathCreateMutable();
CGRect bounds = self.bounds;
CGPathAddRect(path, NULL, bounds);
Sohail Mohabbat Ali | iOS Mentor
15. Advance text Rendering in iOS
What is easy with Core Text
Step 4: Get the Frame
Use the and to create (s), then draw it in
current context
CGContextRef context = UIGraphicsGetCurrentContext();
CTFrameRef frame =
CTFramesetterCreateFrame(framesetter,
CFRangeMake(0, 0),
path, NULL);
CTFrameDraw(frame , context);
Sohail Mohabbat Ali | iOS Mentor
16. Advance text Rendering in iOS
What is easy with Core Text
Step 5: Don’t forget to release them
Release everything you created with CGRelease.
CFRelease(attrString);
CFRelease(framesetter);
CFRelease(frame);
CFRelease(path);
Sohail Mohabbat Ali | iOS Mentor
17. Advance text Rendering in iOS
What is easy with Core Text
Step 5: Don’t forget to release them
Release everything you created with CGRelease.
CFRelease(attrString);
CFRelease(framesetter);
CFRelease(frame);
CFRelease(path);
Sohail Mohabbat Ali | iOS Mentor
18. Advance text Rendering in iOS
How to it ?
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
CGContextTranslateCTM(context, 0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
Sohail Mohabbat Ali | iOS Mentor
19. Advance text Rendering in iOS
Writing on Shapes
CGMutablePathRef path = CGPathCreateMutable();
CTFramesetterRef framesetter =
CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attString);
CTFrameRef theFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0,
[attString length]), path, NULL);
CFRelease(framesetter);
CFRelease(path);
CTFrameDraw(theFrame, context);
CFRelease(theFrame);
Sohail Mohabbat Ali | iOS Mentor
20. Advance text Rendering in iOS
Writing on Shapes (Output)
Sohail Mohabbat Ali | iOS Mentor
21. Advance text Rendering in iOS
Writing on Shapes (Output)
Sohail Mohabbat Ali | iOS Mentor
22. Advance text Rendering in iOS
Playing with NSA Tributed String
With the help of function
we can format different chunks
of strings with different
attributes
Sohail Mohabbat Ali | iOS Mentor
