iOS CoreText类库的详细介绍

iOS 编程中如何使用CoreText类库从框架图中我们可以看出：CTFrame 作为一个整体的画布(Canvas)，其中由行(CTLine)组成，而每行可以分为一个或多个小方块（CTRun）。注意：你不需要自己创建CTRun，Core Text将根据NSAttributedString的属性来自动创建CTRun。每个CTRun对象对应不同的属性，正因此，你可以自由的控制字体、颜色、字间距等等信息。通常处理步聚：1.使用core text就是先有一个要显示的string，然后定义这个string每个部分的样式－>attributedString －> 生成 CTFramesetter -> 得到CTFrame -> 绘制（CTFrameDraw）其中可以更详细的设置换行方式，对齐方式，绘制区域的大小等。2.绘制只是显示，点击事件就需要一个判断了。CTFrame 包含了多个CTLine,并且可以得到各个line的其实位置与大小。判断点击处在不在某个line上。CTLine 又可以判断这个点(相对于ctline的坐标)处的文字范围。然后遍历这个string的所有NSTextCheckingResult，根据result的rang判断点击处在不在这个rang上，从而得到点击的链接与位置。首先，创建工程，添加系统库CoreText

////  CoreTextView.m//  CoreTextDemo////  Created by swplzj on 13-10-30.//  Copyright (c) 2013年 swplzj. All rights reserved.//#import "CoreTextView.h"#import <CoreText/CoreText.h>#import <math.h>@implementation CoreTextViewstatic inline double radians (double degrees){return degrees * M_PI / 180;}void ctLineAndRun(CTFrameRef frame){int lineIndex = 1;//获取frame中的所有行CFArrayRef allLines = CTFrameGetLines(frame);//获取frame中第一行的元素CTLineRef firstLineRef = CFArrayGetValueAtIndex(allLines, lineIndex);//获得frame中所有的行数int linesCount = CFArrayGetCount(allLines);NSLog(@"ctLine的总数量：%d", linesCount);//获取frame中的所有CTRunCFArrayRef ctRun = CTLineGetGlyphRuns(firstLineRef);//    CTRunRef firstRun = CFArrayGetValueAtIndex(ctRun, 0);//    int runsNum = CTLineGetGlyphCount(ctRun);NSLog(@"ctRun的数量：%ld", CFArrayGetCount(ctRun));//按长度截断字符串：省略号NSAttributedString *attributedStr = [[NSAttributedString alloc] initWithString:@"\u2026"];CTLineRef lineToken = CTLineCreateWithAttributedString((CFAttributedStringRef) attributedStr);//截断的方式CTLineTruncationType lineTruncationType = kCTLineTruncationEnd;CTLineRef newLine = CTLineCreateTruncatedLine(firstLineRef, 260, lineTruncationType, lineToken);CGContextRef context = UIGraphicsGetCurrentContext();//重置画布CGContextSetTextMatrix(context, CGAffineTransformIdentity);//保存Context状态CGContextSaveGState(context);CGMutablePathRef path = CGPathCreateMutable();CGRect bounds = CGRectInset((CGRect) {{40, 40}, {320 - 80, 40}}, 0.0f, 0.0f);CGPathAddRect(path, NULL, bounds);CGContextAddPath(context, path);CGContextSetFillColorWithColor(context, [UIColor orangeColor].CGColor);CGContextFillPath(context);CGContextSetTextPosition(context, 40, 40);CTLineDraw(newLine, context);CGPathCloseSubpath(path);CGPathRelease(path);//获取一行文字中，指定charIndex字符(也就是StringRange的Location)相对ctline本身x原点的偏移量（譬如第一个字符很显然是0），返回值与secondaryOffset同为一个值,另外也可以用来求一行字符所占的像素长度//第二个字符index位置是在ctframe整个中的位置，譬如第二行的第一个字符的index是加上第一行所有字符后的indexCGFloat secondaryOffSet;CGFloat primaryOffSet = CTLineGetOffsetForStringIndex(firstLineRef, CTLineGetStringRange(firstLineRef).location, &secondaryOffSet);NSLog(@"第%ld个字符与本身x原点的偏移量:%f",CTLineGetStringRange(firstLineRef).location + 1,primaryOffSet);//获取相对于Flush的偏移量//    CGFloat penOffset = CTLineGetPenOffsetForFlush(firstLine, NSTextAlignmentLeft, 240);//    NSLog(@"相对于Flush的偏移量:%f",penOffset);//CTLineGetStringIndexForPosition 这个方法主要是获得某个ctline中某个位置（position）的character在整个ctframe中的index.这个方法在当有段前缩进或者首行缩进的时候，并不准确，不会跟着缩进而进行偏移，所以段前缩进多少，就需要把position的x值减去多少（譬如段前缩进是20，则要减去20个单位），所以，这个方法最好的用处就是判断一行ctline最多容纳多少的字符，只需把这个point的x位置调很大（超过ctframe path的宽度）就可以了。CGPoint origins[linesCount];CTFrameGetLineOrigins(frame,CFRangeMake(0, 0), origins);CGPoint indexPoint = origins[lineIndex];indexPoint.x -= 20;//段前缩进20,需要减去20//indexPoint.x += 300;可以求CFIndex index = CTLineGetStringIndexForPosition(firstLineRef, indexPoint);NSLog(@"ctframe中%@位置（position）的字符索引:%ld",NSStringFromCGPoint(indexPoint),index);//CTLine在整个文本中所处的range，location是该行前面n行的字符数和，换行符也包括//    CFRange range = CTLineGetStringRange(firstLine);//    NSLog(@"location:%ld=====length:%ld",range.location,range.length);//获取一行中上行高(ascent)，下行高(descent)，行距(leading),整行高为(ascent+|descent|+leading) 返回值为整行字符串长度占有的像素宽度。//    CGFloat asc,des,lead;//    double lineWidth = CTLineGetTypographicBounds(firstLine, &asc, &des, &lead);//    NSLog(@"ascent = %f,descent = %f,leading = %f,lineWidth = %f",asc,des,lead,lineWidth);//获取一行文字最佳可视范围（会把所有文字都包含进去）//    CGRect lineRect = CTLineGetImageBounds(firstLine, context);//    NSLog(@"整行的范围:%@",NSStringFromCGRect(lineRect));CGContextRestoreGState(context);}- (id)initWithFrame:(CGRect)frame{self = [super initWithFrame:frame];if (self) {// Initialization code}return self;}// Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (void)drawRect:(CGRect)rect{NSMutableAttributedString *attributedStr = [[NSMutableAttributedString alloc] initWithString:@"北京出现严重雾霾后，网友纷纷给PM2.5取中文名字。严肃点就叫“公雾源”，高端点就叫“京尘”，霸气点就叫“尘疾思汗”，乐观点就叫“尘世美”，娱乐点就叫“尘惯吸”。但直到那五个字映入眼帘，才明白了中文的强大和词汇的无穷魅力：喂人民服雾！"];[self setAttributedStringParagraphStyle:attributedStr];//    [self setAttributesStringAttributes:attributedStr];CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef) attributedStr);CGMutablePathRef path = CGPathCreateMutable();CGRect bounds = CGRectInset((CGRect) {{20, 100}, {CGRectGetWidth(self.bounds) - 40, 400}}, 10.0f, 10.0f);CGPathAddRect(path, NULL, bounds);CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), path, NULL);CGContextRef context = UIGraphicsGetCurrentContext();CGContextTranslateCTM(context, 0, self.bounds.size.height);//转换CTMCGContextScaleCTM(context, 1.0, -1.0);CGContextSaveGState(context);//向图形状态栈中保存context状态//ctLine的相关操作ctLineAndRun(frame);CGContextSetTextMatrix(context, CGAffineTransformIdentity);//重置画布CGContextAddPath(context, path);CGContextSetFillColorWithColor(context, [UIColor yellowColor].CGColor);CGContextFillPath(context);//CTLineGetImageBounds的应用，获取一行文字的范围， 就是指把这一行文字点有的像素矩阵作为一个image图片，来得到整个矩形区域CFArrayRef Lines = CTFrameGetLines(frame);int lineCount = CFArrayGetCount(Lines);CGPoint origins[lineCount];CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), origins);NSInteger lineIndex = 0;for (id oneLine in (NSArray *)Lines) {//相对于每一行基线原点的偏移量和宽高（例如：{{1.2， -2.57227}, {208.025, 19.2523}}，就是相对于本身的基线原点向右偏移1.2个单位，向下偏移2.57227个单位，后面是宽高）CGRect lineBounds = CTLineGetImageBounds((CTLineRef)oneLine, context);//每一行的起始点（相对于context）加上相对于本身基线原点的偏移量lineBounds.origin.x += origins[lineIndex].x + 30;lineBounds.origin.y += origins[lineIndex].y + 110;lineIndex++;//填充CGContextSetStrokeColorWithColor(context, [[UIColor redColor] CGColor]);CGContextSetLineWidth(context, 1.0);//设置长方形4个顶点CGPoint points[] = {CGPointMake(lineBounds.origin.x, lineBounds.origin.y), CGPointMake(lineBounds.origin.x + lineBounds.size.width, lineBounds.origin.y), CGPointMake(lineBounds.origin.x + lineBounds.size.width, lineBounds.origin.y + lineBounds.size.height), CGPointMake(lineBounds.origin.x, lineBounds.origin.y + lineBounds.size.height)};CGContextAddLines(context, points, 4);CGContextClosePath(context);CGContextStrokePath(context);}//画CTFrameDraw(frame, context);CGPathRelease(path);CFRelease(frame);CFRelease(frameSetter);//恢复状态栈中原有的状态CGContextRestoreGState(context);}- (void)setAttributesStringAttributes:(NSMutableAttributedString *)attributedString{//设置字体CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"), 20, NULL);[attributedString addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];//设置字间距long kernNumber = 5;CFNumberRef kernNum = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt8Type, &kernNumber);[attributedString addAttribute:(id)kCTKernAttributeName value:(id)kernNum range:(NSRange){0, 4}];//设置字体颜色long strokeNumber = 2;CFNumberRef strokeNum = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt8Type, &strokeNumber);[attributedString addAttribute:(id)kCTStrokeWidthAttributeName value:(id)strokeNum range:(NSRange){0, 4}];[attributedString addAttribute:(id)kCTStrokeColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 4)];//设置下划线[attributedString addAttribute:(id)kCTUnderlineStyleAttributeName value:(id)[NSNumber numberWithInt:kCTUnderlineStyleSingle] range:NSMakeRange(0, 4)];[attributedString addAttribute:(id)kCTUnderlineStyleAttributeName value:(id)[UIColor redColor] range:(NSRange){0, 4}];//多属性设置UIColor *color = [UIColor redColor];NSMutableDictionary *attributes = [[NSMutableDictionary alloc] initWithObjectsAndKeys:(id)font, kCTFontAttributeName, kernNum, kCTKernAttributeName, color.CGColor, kCTForegroundColorAttributeName, nil];[attributedString setAttributes:attributes range:NSMakeRange(0, 4)];}- (void)setAttributedStringParagraphStyle:(NSMutableAttributedString *)attributedString{//对齐方式CTTextAlignment textAlignment = kCTLeftTextAlignment;CTParagraphStyleSetting alignmentStyleSetting;alignmentStyleSetting.spec = kCTParagraphStyleSpecifierAlignment;alignmentStyleSetting.valueSize = sizeof(textAlignment);alignmentStyleSetting.value = &textAlignment;//首行缩进CGFloat firstLineIndentSize = 55.0f;CTParagraphStyleSetting firstLineIndent;firstLineIndent.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;firstLineIndent.value = &firstLineIndentSize;firstLineIndent.valueSize = sizeof(float);//段前缩进（文字左侧距离context最左侧的距离）CGFloat headIndentSize = 20.0f;CTParagraphStyleSetting headIndent;headIndent.spec = kCTParagraphStyleSpecifierHeadIndent;headIndent.valueSize = sizeof(float);headIndent.value = &headIndentSize;//断尾缩进(文字右侧距离context最左侧的距离)CGFloat tailIndentSize = 251.0f;    //文字最左侧到文字最右侧的距离CTParagraphStyleSetting tailIndent;tailIndent.spec = kCTParagraphStyleSpecifierTailIndent;tailIndent.value = &tailIndentSize;tailIndent.valueSize = sizeof(float);//换行模式CTLineBreakMode lineBreak = kCTLineBreakByCharWrapping;CTParagraphStyleSetting lineBreakMode;lineBreakMode.spec = kCTParagraphStyleSpecifierLineBreakMode;lineBreakMode.value = &lineBreak;lineBreakMode.valueSize = sizeof(CTLineBreakMode);//最大行高CGFloat maxHeightSize = 50.0f;  //最大行高不能超过50个像素，超过按照最大像素来CTParagraphStyleSetting maxHeightSetting;maxHeightSetting.spec = kCTParagraphStyleSpecifierMaximumLineHeight;maxHeightSetting.value = &maxHeightSize;maxHeightSetting.valueSize = sizeof(float);//多行高CGFloat multipleHeight = 1.2f;  //1.2倍原来的高度CTParagraphStyleSetting multipleHeightSetting;multipleHeightSetting.spec = kCTParagraphStyleSpecifierLineHeightMultiple;multipleHeightSetting.value = &multipleHeight;multipleHeightSetting.valueSize = sizeof(float);//最大行距CGFloat maxLineSpace = 5.0f;//最大行距不能超过5像素，超过了按最大行距画图，最小行距同理，行距调整只在中间值中进行CTParagraphStyleSetting maxLineSpaceSetting;maxLineSpaceSetting.spec = kCTParagraphStyleSpecifierMaximumLineSpacing;maxLineSpaceSetting.valueSize = sizeof(float);maxLineSpaceSetting.value = &maxLineSpace;//行距CGFloat lineSpace = 25.0f;  //行距25像素CTParagraphStyleSetting lineSpaceSetting;lineSpaceSetting.spec = kCTParagraphStyleSpecifierLineSpacing;lineSpaceSetting.value = &lineSpace;lineSpaceSetting.valueSize = sizeof(float);//段前间隔CGFloat paragraghSpace = 15.0f;CTParagraphStyleSetting paragraghInterval;paragraghInterval.spec = kCTParagraphStyleSpecifierParagraphSpacing;paragraghInterval.valueSize = sizeof(float);paragraghInterval.value = ¶graghSpace;CTParagraphStyleSetting settingsArray[] = {alignmentStyleSetting, firstLineIndent, headIndent, tailIndent, lineBreakMode, maxLineSpaceSetting, multipleHeightSetting, lineSpaceSetting, maxLineSpaceSetting, paragraghInterval};//采用setting里面前10个的段落设置，不够10个，就按照setting拥有的最大段落设置个数来算CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(settingsArray, 10);NSDictionary *paragraphStyleDic = [[NSDictionary alloc] initWithObjectsAndKeys:(id)paragraphStyle, kCTParagraphStyleAttributeName, nil];[attributedString setAttributes:paragraphStyleDic range:(NSRange){0, [attributedString length]}];}- (void)ctLineAndRun{}@end

关于CoreText的官方API： https://developer.apple.com/library/mac/#documentation/Carbon/Reference/CoreText_Framework_Ref/_index.html