coreText基础知识

 

 

首先，进行创建一个UIView的子类，并实现如下代码:

- (void)drawRect:(CGRect)rect {
// Drawing code.

//创建要输出的字符串
NSString *longText = @”袁唯来来 Lorem ipsum dolor sit amet, Before the iPad was released you had basically two ways how to get text on screen. Either you would stick with UILabel or UITextView provided by UIKit or if you felt hard-core you would draw the text yourself on the Quartz level incurring all the headaches induced by having to mentally switch between Objective-C and C API functions.\
As of iOS 3.2 we gained a third alternative in Core Text promising full control over styles, thread safety and performance. However for most of my apps I did not want to break 3.x compatibility and so I procrastinated looking at this powerful new API. Apps running only on iPads could have made use of Core Text from day 1, but to me it made more sense supporting iPad via hybrid apps where the iPhone part would still be backwards compatible.\
Now as the year has turned the adoption of 4.x on all iOS platforms is ever more accelerating. Many new iPads where found under the Christmas tree and by now even the most stubborn people (read needing 3.x for jailbreaking and sim-unlocking) have little reason to stick with 3.x. Thus we have almost no incentive left to stick with 3.x compatibility. Yay!”;

//创建AttributeString
NSMutableAttributedString *string = [[NSMutableAttributedString alloc]
initWithString:longText];

//创建字体以及字体大小
CTFontRef helvetica = CTFontCreateWithName(CFSTR(”Helvetica”), 14.0, NULL);
CTFontRef helveticaBold = CTFontCreateWithName(CFSTR(”Helvetica-Bold”), 14.0, NULL);

//添加字体 目标字符串从下标0开始到字符串结尾
[string addAttribute:(id)kCTFontAttributeName
value:(id)helvetica
range:NSMakeRange(0, [string length])];

//添加字体 目标字符串从下标0开始，截止到4个单位的长度
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(0, 4)];

//添加字体 目标字符串从下标6开始，截止到5个单位长度
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(6, 5)];

//添加字体 目标字符串从下标109开始，截止到9个单位长度
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(109, 9)];

//添加字体 目标字符串从下标223开始，截止到6个单位长度
[string addAttribute:(id)kCTFontAttributeName
value:(id)helveticaBold
range:NSMakeRange(223, 6)];

//添加颜色，目标字符串从下标0开始，截止到4个单位长度
[string addAttribute:(id)kCTForegroundColorAttributeName
value:(id)[UIColor blueColor].CGColor
range:NSMakeRange(0, 4)];

//添加过程同上
[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)];

//创建文本对齐方式
CTTextAlignment alignment = kCTLeftTextAlignment;//左对齐 kCTRightTextAlignment为右对齐
CTParagraphStyleSetting alignmentStyle;
alignmentStyle.spec=kCTParagraphStyleSpecifierAlignment;//指定为对齐属性
alignmentStyle.valueSize=sizeof(alignment);
alignmentStyle.value=&alignment;

//创建文本行间距
CGFloat lineSpace=5.0f;//间距数据
CTParagraphStyleSetting lineSpaceStyle;
lineSpaceStyle.spec=kCTParagraphStyleSpecifierLineSpacing;//指定为行间距属性
lineSpaceStyle.valueSize=sizeof(lineSpace);
lineSpaceStyle.value=&lineSpace;

//创建样式数组
CTParagraphStyleSetting settings[]={
alignmentStyle,lineSpaceStyle
};

//设置样式
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(settings, sizeof(settings));

//给字符串添加样式attribute
[string addAttribute:(id)kCTParagraphStyleAttributeName
value:(id)paragraphStyle
range:NSMakeRange(0, [string length])];

// layout master
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(
(CFAttributedStringRef)string);

CGMutablePathRef leftColumnPath = CGPathCreateMutable();
CGPathAddRect(leftColumnPath, NULL,
CGRectMake(0, 0,
self.bounds.size.width,
self.bounds.size.height));

CTFrameRef leftFrame = CTFramesetterCreateFrame(framesetter,
CFRangeMake(0, 0),
leftColumnPath, 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);

// cleanup

CGPathRelease(leftColumnPath);
CFRelease(framesetter);
CFRelease(helvetica);
CFRelease(helveticaBold);
[string release];
UIGraphicsPushContext(context);

}