1。绘制简单的一行文字
- (void)drawRect:(CGRect)rect
{
// create a font, quasi systemFontWithSize:24.0
CTFontRef sysUIFont = CTFontCreateUIFontForLanguage(kCTFontSystemFontType,
24.0, NULL);
// create a naked string
NSString *string = @"Some Text";
// blue
CGColorRef color = [UIColor blueColor].CGColor;
// single underline
NSNumber *underline = [NSNumber numberWithInt:kCTUnderlineStyleSingle];
// pack it into attributes dictionary
NSDictionary *attributesDict = [NSDictionary dictionaryWithObjectsAndKeys:
(id)sysUIFont, (id)kCTFontAttributeName,
color, (id)kCTForegroundColorAttributeName,
underline, (id)kCTUnderlineStyleAttributeName, nil];
// make the attributed string
NSAttributedString *stringToDraw = [[NSAttributedString alloc] initWithString:string
attributes:attributesDict];
// now for the actual drawing
CGContextRef context = UIGraphicsGetCurrentContext();
// flip the coordinate system
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
CGContextTranslateCTM(context, 0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// draw
CTLineRef line = CTLineCreateWithAttributedString(
(CFAttributedStringRef)stringToDraw);
CGContextSetTextPosition(context, 10.0, 10.0);
CTLineDraw(line, context);
// clean up
CFRelease(line);
CFRelease(sysUIFont);
[stringToDraw release];
}
2。实现分列的文本显示
实现的效果如下：
- (void)drawRect:(CGRect)rect
{
NSString *longText = @"Lorem ipsum dolor sit amet, "; /* ... */
NSMutableAttributedString *string = [[NSMutableAttributedString alloc]
initWithString:longText];
// make a few words bold
CTFontRef helvetica = CTFontCreateWithName(CFSTR("Helvetica"), 14.0, NULL);
CTFontRef helveticaBold = CTFontCreateWithName(CFSTR("Helvetica-Bold"), 14.0, NULL);
[string addAttribute:(id)kCTFontAttributeName
value:(id)helvetica
range:NSMakeRange(0, [string length])];
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(6, 5)];
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(109, 9)];
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(223, 6)];
// add some color
[string addAttribute:(id)kCTForegroundColorAttributeName
value:(id)[UIColor redColor].CGColor
range:NSMakeRange(18, 3)];
[string addAttribute:(id)kCTForegroundColorAttributeName
value:(id)[UIColor greenColor].CGColor
range:NSMakeRange(657, 6)];
[string addAttribute:(id)kCTForegroundColorAttributeName
value:(id)[UIColor blueColor].CGColor
range:NSMakeRange(153, 6)];
// layout master
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(
(CFAttributedStringRef)string);
// left column form
CGMutablePathRef leftColumnPath = CGPathCreateMutable();
CGPathAddRect(leftColumnPath, NULL,
CGRectMake(0, 0,
self.bounds.size.width/2.0,
self.bounds.size.height));
// left column frame
CTFrameRef leftFrame = CTFramesetterCreateFrame(framesetter,
CFRangeMake(0, 0),
leftColumnPath, NULL);
// right column form
CGMutablePathRef rightColumnPath = CGPathCreateMutable();
CGPathAddRect(rightColumnPath, NULL,
CGRectMake(self.bounds.size.width/2.0, 0,
self.bounds.size.width/2.0,
self.bounds.size.height));
NSInteger rightColumStart = CTFrameGetVisibleStringRange(leftFrame).length;
// right column frame
CTFrameRef rightFrame = CTFramesetterCreateFrame(framesetter,
CFRangeMake(rightColumStart, 0),
rightColumnPath,
NULL);
// flip the coordinate system
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
CGContextTranslateCTM(context, 0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// draw
CTFrameDraw(leftFrame, context);
CTFrameDraw(rightFrame, context);
// cleanup
CFRelease(leftFrame);
CGPathRelease(leftColumnPath);
CFRelease(rightFrame);
CGPathRelease(rightColumnPath);
CFRelease(framesetter);
CFRelease(helvetica);
CFRelease(helveticaBold);
[string release];
}
布局功能：
下划线功能：
// pack it into attributes dictionary
NSDictionary *attributesDict = [NSDictionary dictionaryWithObjectsAndKeys:
(id)sysUIFont, (id)kCTFontAttributeName,
color, (id)kCTForegroundColorAttributeName,
underline, (id)kCTUnderlineStyleAttributeName, nil];
Underlining is not a feature of the font itself, but of NSAttributedString, likely because you can underline text in ANY font. These are your options:
None
Single Line
Double Line
Thick Line
These can be bitwise OR combined with several underlining line styles:
Solid Line
Dotted Line
Dashed Line
Dash-Dotted Line
Dash-Dot-Dotted Lin
删除线功能
// add custom attribute
[string addAttribute:@"DTCustomStrikeOut"
value:[NSNumber numberWithBool:YES]
range:NSMakeRange(18, 138)];
// reset text position
CGContextSetTextPosition(context, 0, 0);
// get lines
CFArrayRef leftLines = CTFrameGetLines(leftFrame);
CGPoint *origins = malloc(sizeof(CGPoint)*[(NSArray *)leftLines count]);
CTFrameGetLineOrigins(leftFrame,
CFRangeMake(0, 0), origins);
NSInteger lineIndex = 0;
for (id oneLine in (NSArray *)leftLines)
{
CFArrayRef runs = CTLineGetGlyphRuns((CTLineRef)oneLine);
CGRect lineBounds = CTLineGetImageBounds((CTLineRef)oneLine, context);
lineBounds.origin.x += origins[lineIndex].x;
lineBounds.origin.y += origins[lineIndex].y;
lineIndex++;
CGFloat offset = 0;
for (id oneRun in (NSArray *)runs)
{
CGFloat ascent = 0;
CGFloat descent = 0;
CGFloat width = CTRunGetTypographicBounds((CTRunRef) oneRun,
CFRangeMake(0, 0),
&ascent,
&descent, NULL);
NSDictionary *attributes = (NSDictionary *)CTRunGetAttributes((CTRunRef) oneRun);
BOOL strikeOut = [[attributes objectForKey:@"DTCustomStrikeOut"] boolValue];
if (strikeOut)
{
CGRect bounds = CGRectMake(lineBounds.origin.x + offset,
lineBounds.origin.y,
width, ascent + descent);
// don't draw too far to the right
if (bounds.origin.x + bounds.size.width > CGRectGetMaxX(lineBounds))
{
bounds.size.width = CGRectGetMaxX(lineBounds) - bounds.origin.x;
}
// get text color or use black
id color = [attributes objectForKey:(id)kCTForegroundColorAttributeName];
if (color)
{
CGContextSetStrokeColorWithColor(context, (CGColorRef)color);
}
else
{
CGContextSetGrayStrokeColor(context, 0, 1.0);
}
CGFloat y = roundf(bounds.origin.y + bounds.size.height / 2.0);
CGContextMoveToPoint(context, bounds.origin.x, y);
CGContextAddLineToPoint(context, bounds.origin.x + bounds.size.width, y);
CGContextStrokePath(context);
}
offset += width;
}
}
// cleanup
free(origins);
详细介绍：
http://www.cocoanetics.com/2011/01/befriending-core-text/