iOS 项目小结

1.iOS中的round、ceil、floor函数略解

round如果参数是小数，则求本身的四舍五入.ceil如果参数是小数，则求最小的整数但不小于本身.floor如果参数是小数，则求最大的整数但不大于本身.

Example:如何值是3.4的话，则

-- round 3.000000

-- ceil 4.000000

-- floor 3.00000

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CoreText（四）：行 CTLineRef

标签：字体 coretext

2016-09-08 18:14241人阅读评论(0)收藏举报

分类：

iOS连载（8）

目录(?)[+]

一、字符(Character)和字形(Glyphs)

排版过程中一个重要的步骤就是从字符到字形的转换，字符表示信息本身，而字形是它的图形表现形式。字符一般就是指某种编码，如Unicode编码，而字形则是这些编码对应的图片。但是他们之间不是一一对应关系，同个字符的不同字体族，不同字体大小，不同字体样式都对应了不同的字形。而由于连写(Ligatures)的存在，多个字符也会存在对应一个字形的情况。

下面就来详情看看字形的各个参数也就是所谓的字形度量Glyph Metrics

（1）、边界框 bbox(bounding box)

这是一个假想的框子，它尽可能紧密的装入字形。

（2）、基线(baseline)

一条假想的线,一行上的字形都以此线作为上下位置的参考，在这条线的左侧存在一个点叫做基线的原点，

（3）、上行高度(ascent)

从原点到字体中最高（这里的高深都是以基线为参照线的）的字形的顶部的距离，ascent是一个正值

（4）、下行高度(descent)

从原点到字体中最深的字形底部的距离，descent是一个负值（比如一个字体原点到最深的字形的底部的距离为2，那么descent就为-2）

（5）、行距(line gap)

line gap也可以称作leading（其实准确点讲应该叫做External leading）,行高line Height则可以通过 ascent + |descent| + linegap 来计算。

（6）、字间距(Kerning)

字与字之间的距离，为了排版的美观，并不是所有的字形之间的距离都是一致的，但是这个基本步影响到我们的文字排版。

（7）、基础原点(Origin)

基线上最左侧的点。

红框高度既为当前行的行高，绿线为baseline，绿色到红框上部分为当前行的最大Ascent，绿线到黄线为当前行的最大Desent，而黄框的高即为行间距。由此可以得出：lineHeight = Ascent + |Decent| + Leading。

二、坐标系

传统的Mac中的坐标系的原点在左下角，比如NSView默认的坐标系，原点就在左下角。但Mac中有些View为了其实现的便捷将原点变换到左上角，像NSTableView的坐标系坐标原点就在左上角。

iOSUIKit中，UIView是以左上角为原点，而Core Text一开始的定位是使用与桌面应用的排版系统，桌面应用的坐标系是以左下角为原点，即Core Text在绘制的时候也是参照左下角为原点进行绘制的，所以需要对当前的坐标系进行处理。

实际上，Core Graphic 中的context也是以左下角为原点的，但是为什么我们用Core Graphic

绘制一些简单的图形的时候不需要对坐标系进行处理呢，是因为通过这个方法UIGraphicsGetCurrentContext()来获得的当前context是已经被处理过的了，用下面方法可以查看指定的上下文的当前图形状态变换矩阵。

方法一

//因为Core Text要配合Core Graphic 配合使用的，如Core Graphic一样，绘图的时候需要获得当前的上下文进行绘制CGContextRef context = UIGraphicsGetCurrentContext();NSLog(@"当前context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));//翻转当前的坐标系（因为对于底层绘制引擎来说，屏幕左下角为（0，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);//设置字形变换矩阵为CGAffineTransformIdentity，也就是说每一个字形都不做图形变换CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);CGContextConcatCTM(context, flipVertical);//将当前context的坐标系进行flipNSLog(@"翻转后context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));

打印结果为：

当前context的变换矩阵[2, 0, 0, -2, 0, 800]翻转后context的变换矩阵[2, 0, 0, 2, 0, 0]

方法二

//因为Core Text要配合Core Graphic 配合使用的，如Core Graphic一样，绘图的时候需要获得当前的上下文进行绘制CGContextRefcontext= UIGraphicsGetCurrentContext();NSLog(@"当前context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));//翻转当前的坐标系（因为对于底层绘制引擎来说，屏幕左下角为（0，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);CGContextTranslateCTM(context,0, self.bounds.size.height);CGContextScaleCTM(context,1.0, -1.0);NSLog(@"翻转后context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));

打印：

当前context的变换矩阵[2, 0, 0, -2, 0, 800]翻转后context的变换矩阵[2, 0, -0, 2, 0, 0]

可以发现变换矩阵与CGAffineTransformIdentity的值[1, 0, 0, 1, 0,

0]是不相同的，并且与设备是否为Retina屏和设备尺寸相关。他的作用是将上下文空间坐标系进行翻转，并使原来的左下角原点变成左上角是原点，并将向上为正y轴变为向下为正y轴。

所以在使用drawRect的时候，当前的context已经被做了一次翻转，如果不对当前的坐标系进行处理，会发现，绘制出来的文字是镜像上下颠倒的。所以在UIView的drawRect方法中的context上进行Core

Text绘制之前需要对context进行一次Flip。

三、主要函数

1、传入CTFrame，返回一个装有多个CTLine对象的数组。

CFArrayRefCTFrameGetLines(

CTFrameRef frame )CT_AVAILABLE(10_5,3_2);

2、获取数组中的元素个数

CFIndexCFArrayGetCount(CFArrayRef theArray);

3、获取数组中第idx个元素

constvoid*CFArrayGetValueAtIndex(CFArrayRef theArray, CFIndex idx);

4、获取所有CTLineRef的基础原点，传入CTFrame，CFRange，和一个CGPoint的结构体数组指针，该函数会把每一个CTLine的origin坐标写到数组里。

voidCTFrameGetLineOrigins( CTFrameRef frame, CFRange range,CGPointorigins[] ) CT_AVAILABLE(10_5,3_2);

5、获取CTLine中文字在整段文字中的Range

CFRangeCTLineGetStringRange(

CTLineRef line )CT_AVAILABLE(10_5,3_2);

6、获取CTLine中的CTRun的数组

CFArrayRefCTLineGetGlyphRuns(

CTLineRef line )CT_AVAILABLE(10_5,3_2);

7、获取CTRun在整段文字中的Range

CFRangeCTRunGetStringRange(

CTRunRef run )CT_AVAILABLE(10_5,3_2);

8、获取点击处position文字在整段文字中的index

CFIndexCTLineGetStringIndexForPosition(

CTLineRef line,

CGPoint position )CT_AVAILABLE(10_5,3_2);

9、获取整段文字中charIndex位置的字符相对line的原点的x值

CGFloatCTLineGetOffsetForStringIndex( CTLineRef line, CFIndex charIndex,CGFloat* __nullable secondaryOffset ) CT_AVAILABLE(10_5,3_2);

10、获取数组中字形个个数

CFIndexCTLineGetGlyphCount(

CTLineRef line )CT_AVAILABLE(10_5,3_2);

11、设置CoreText绘制前的坐标。设置基线位置

CG_EXTERNvoidCGContextSetTextPosition(CGContextRef __nullable c,CGFloatx,CGFloaty) CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

12、绘制CTLine。

voidCTLineDraw(

CTLineRef line,

CGContextRef context )CT_AVAILABLE(10_5,3_2);

13、获取CTLine的上行高度，下行高度，行距

doubleCTLineGetTypographicBounds( CTLineRef line,CGFloat* __nullable ascent,CGFloat* __nullable descent,CGFloat* __nullable leading ) CT_AVAILABLE(10_5,3_2);

14、设置当前文本矩阵

CG_EXTERN voidCGContextSetTextMatrix(CGContextRef __nullable c,

CGAffineTransform t)CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

15、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。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）

CGRectCTLineGetImageBounds(

CTLineRef line,

CGContextRef __nullable context )CT_AVAILABLE(10_5,3_2);

例如：

//获取frame中CTLineRef数组CFArrayRef Lines = CTFrameGetLines(frame);//获取数组Lines中的个数CFIndex lineCount = CFArrayGetCount(Lines);//获取数组中第一个CTLineRefCTLineRef lineRef = CFArrayGetValueAtIndex(Lines,0);//获取lineRef中CTRunRef数组CFArrayRef runs = CTLineGetGlyphRuns(lineRef);//获取CTLineRef中字形个数CFIndex rus = CTLineGetGlyphCount(lineRef);//获取数组runs中的个数CFIndex runCount = CFArrayGetCount(runs);NSLog(@"lines =%ldruns =%ldrus =%ld",lineCount,runCount,rus);

打印：

lines=7 runs = 5 rus = 37

四、举例

1、绘框

- (void)drawRect:(CGRect)rect{// 步骤1：得到当前用于绘制画布的上下文，用于后续将内容绘制在画布上// 因为Core Text要配合Core Graphic 配合使用的，如Core Graphic一样，绘图的时候需要获得当前的上下文进行绘制CGContextRef context = UIGraphicsGetCurrentContext();NSLog(@"当前context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步骤2：翻转当前的坐标系（因为对于底层绘制引擎来说，屏幕左下角为（0，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);//设置字形变换矩阵为CGAffineTransformIdentity，也就是说每一个字形都不做图形变换CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height); CGContextConcatCTM(context, flipVertical);//将当前context的坐标系进行flipNSLog(@"翻转后context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步骤3：创建绘制区域CGMutablePathRef path = CGPathCreateMutable(); CGPathAddRect(path,NULL,self.bounds);// 步骤4：创建需要绘制的文字与计算需要绘制的区域NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:@"iOS程序在启动时会创建一个主线程，而在一个线程只能执行一件事情，如果在主线程执行某些耗时操作，例如加载网络图片，下载资源文件等会阻塞主线程（导致界面卡死，无法交互），所以就需要使用多线程技术来避免这类情况。iOS中有三种多线程技术 NSThread，NSOperation，GCD，这三种技术是随着IOS发展引入的，抽象层次由低到高，使用也越来越简单。"];// 步骤5：根据AttributedString生成CTFramesetterRefCTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString); CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, [attrString length]), path,NULL);//获取frame中CTLineRef数组CFArrayRef Lines = CTFrameGetLines(frame);//获取数组Lines中的个数CFIndex lineCount = CFArrayGetCount(Lines);//获取基线原点CGPointorigins[lineCount]; CTFrameGetLineOrigins(frame, CFRangeMake(0,0), origins);for(CFIndex i =0; i < lineCount; i ++) { CTLineRef line = CFArrayGetValueAtIndex(Lines, i);//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）CGRectlineBounds = CTLineGetImageBounds((CTLineRef)line, context);NSLog(@"lineBounds = %@",NSStringFromCGRect(lineBounds));NSLog(@"point = %@",NSStringFromCGPoint(origins[i]));//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[i].x; lineBounds.origin.y+= origins[i].y;//填充CGContextSetLineWidth(context,1.0); CGContextAddRect(context,lineBounds); CGContextSetStrokeColorWithColor(context, [[UIColorredColor] CGColor]); CGContextStrokeRect(context, lineBounds); }// 步骤6：进行绘制CTFrameDraw(frame, context);// 步骤7.内存管理CFRelease(frame); CFRelease(path); CFRelease(frameSetter);}

打印：

当前context的变换矩阵 [2,0,0,-2,0,800]翻转后context的变换矩阵 [2,0,0,2,0,0]lineBounds={{0.7734375,-2.052}, {354.70246875000004, 11.964}}point= {0,387}lineBounds={{0.44400000000000001,-2.052}, {371.06400000000002, 11.94}}point= {0,370}lineBounds={{0.38400000000000001,-2.052}, {371.06400000000002, 11.975999999999999}}point= {0,353}lineBounds={{0.41999999999999998,-2.052}, {320.66929687499999, 11.927999999999999}}point= {0,336}lineBounds={{0.9140625,-2.501953125}, {366.28096875, 12.473953125}}point= {0,319}lineBounds={{0.40800000000000003,-2.052}, {148.16400000000002, 11.94}}point= {0,302}

2、单行绘制

- (void)drawRect:(CGRect)rect{// 步骤1：得到当前用于绘制画布的上下文，用于后续将内容绘制在画布上// 因为Core Text要配合Core Graphic 配合使用的，如Core Graphic一样，绘图的时候需要获得当前的上下文进行绘制CGContextRef context = UIGraphicsGetCurrentContext();NSLog(@"当前context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步骤2：翻转当前的坐标系（因为对于底层绘制引擎来说，屏幕左下角为（0，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);//设置字形变换矩阵为CGAffineTransformIdentity，也就是说每一个字形都不做图形变换CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height); CGContextConcatCTM(context, flipVertical);//将当前context的坐标系进行flipNSLog(@"翻转后context的变换矩阵 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步骤3：创建绘制区域CGMutablePathRef path = CGPathCreateMutable(); CGPathAddRect(path,NULL,self.bounds);// 步骤4：创建需要绘制的文字与计算需要绘制的区域NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:@"门梁真可怕当中英文混合之后，��会出现行高不统一的情况，现在在绘制的时候根据字体的descender来偏移绘制，对齐baseline。��同时点击链接的时候会调用drawRect: 造成绘制异常，所以将setNeedsDisplay注释，如需刷新，请手动调用。带上emoji以供测试��"]; CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"),20,NULL); [attrString addAttribute:(id)kCTFontAttributeName value:(__bridgeid)font range:NSMakeRange(0, attrString.length)];// 步骤5：根据AttributedString生成CTFramesetterRefCTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString); CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, [attrString length]), path,NULL);//获取frame中CTLineRef数组CFArrayRef Lines = CTFrameGetLines(frame);//获取数组Lines中的个数CFIndex lineCount = CFArrayGetCount(Lines);//获取基线原点CGPointorigins[lineCount]; CTFrameGetLineOrigins(frame, CFRangeMake(0,0), origins);for(CFIndex i =0; i < lineCount; i ++) { CTLineRef line = CFArrayGetValueAtIndex(Lines, i);//遍历每一行CTLineCGFloatlineAscent;CGFloatlineDescent;CGFloatlineLeading;// 行距// 该函数除了会设置好ascent,descent,leading之外，还会返回这行的宽度CTLineGetTypographicBounds(line, &lineAscent, &lineDescent, &lineLeading);NSLog(@"lineAscent = %f",lineAscent);NSLog(@"lineDescent = %f",lineDescent);NSLog(@"lineLeading = %f",lineLeading);CGPointlineOrigin = origins[i];NSLog(@"point = %@",NSStringFromCGPoint(lineOrigin));CGRectoldLineBounds = CTLineGetImageBounds((CTLineRef)line, context);NSLog(@"lineBounds改动前：%@",NSStringFromCGRect(oldLineBounds));NSLog(@"y = %f d = %f fontD = %f",lineOrigin.y,lineDescent,CTFontGetDescent(font));NSLog(@"Position修改前%@",NSStringFromCGPoint(CGContextGetTextPosition(context))); CGContextSetTextPosition(context, lineOrigin.x, lineOrigin.y-lineDescent - CTFontGetDescent(font));NSLog(@"Position修改后%@",NSStringFromCGPoint(CGContextGetTextPosition(context)));CGRectlineBounds = CTLineGetImageBounds((CTLineRef)line, context);NSLog(@"lineBounds改动后 = %@",NSStringFromCGRect(lineBounds));//填充CGContextSetLineWidth(context,1.0); CGContextAddRect(context,lineBounds); CGContextSetStrokeColorWithColor(context, [[UIColorredColor] CGColor]); CGContextStrokeRect(context, lineBounds); CTLineDraw(line, context);//绘制原点为左下角}// 步骤6：进行绘制// CTFrameDraw(frame, context);// 步骤7.内存管理CFRelease(frame); CFRelease(path); CFRelease(frameSetter);}

打印数据：

当前context的变换矩阵 [2,0,0, -2,0,800]翻转后context的变换矩阵 [2,0,0,2,0,0]lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 378}lineBounds改动前：{{1.98, -3.5499999999999998},{328.34421874999998, 22}}y =378.000000d =6.875000fontD =4.384766Position修改前{0, 0}Position修改后{0, 366.740234375}lineBounds改动后 ={{1.98, 363.19023437499999},{328.34421874999998, 22}}lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 349}lineBounds改动前：{{331.32421875, 363.19023437499999},{367.41999999999996, 22}}y =349.000000d =6.875000fontD =4.384766Position修改前{330.82421875, 366.740234375}Position修改后{0, 337.740234375}lineBounds改动后 ={{0.5, 334.19023437499999},{367.41999999999996, 22}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 321}lineBounds改动前：{{369.83999999999997, 335.58023437499997},{368.16703124999998, 18.66}}y =321.000000d =6.800000fontD =4.384766Position修改前{369, 337.740234375}Position修改后{0, 309.81523437499999}lineBounds改动后 ={{0.83999999999999997, 307.65523437499996},{368.16703124999998, 18.66}}lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 292}lineBounds改动前：{{370.40703124999999, 306.26523437499998},{365.81625000000003, 22}}y =292.000000d =6.875000fontD =4.384766Position修改前{369.70703125, 309.81523437499999}Position修改后{0, 280.740234375}lineBounds改动后 ={{0.70000000000000007, 277.19023437499999},{365.81625000000003, 22}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 264}lineBounds改动前：{{368.41624999999999, 278.58023437499997},{353.68367187500002, 18.620000000000001}}y =264.000000d =6.800000fontD =4.384766Position修改前{367.65625, 280.740234375}Position修改后{0, 252.81523437499999}lineBounds改动后 ={{0.76000000000000001, 250.65523437499999},{353.68367187500002, 18.620000000000001}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 236}lineBounds改动前：{{356.94367187500001, 248.47929687499999},{363.27226562499999, 20.775937499999998}}y =236.000000d =6.800000fontD =4.384766Position修改前{355.263671875, 252.81523437499999}Position修改后{0, 224.81523437499999}lineBounds改动后 ={{1.6799999999999999, 220.47929687499999},{363.27226562499999, 20.775937499999998}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 208}lineBounds改动前：{{367.25226562500001, 220.47929687499999},{328.44562499999995, 20.915937499999998}}y =208.000000d =6.800000fontD =4.384766Position修改前{366.572265625, 224.81523437499999}Position修改后{0, 196.81523437499999}lineBounds改动后 ={{0.68000000000000005, 192.47929687499999},{328.44562499999995, 20.915937499999998}}lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 179}lineBounds改动前：{{330.265625, 193.26523437499998},{229, 22}}y =179.000000d =6.875000fontD =4.384766Position修改前{329.765625, 196.81523437499999}Position修改后{0, 167.740234375}lineBounds改动后 ={{0.5, 164.19023437499999},{229, 22}}

3、固定行间距

行高=每行的asent + 每行的descent + 行数*行间距

#import"MyView.h"#import// 行距constCGFloatkGlobalLineLeading =5.0;@interfaceMyView()@property(nonatomic,assign)CGFloattextHeight;@end@implementationMyView- (instancetype)initWithFrame:(CGRect)frame{self= [superinitWithFrame:frame];if(self) {self.text= @"我自横刀向天笑，去留肝胆两昆仑。--谭嗣同同学你好啊。This is my first CoreText demo,how are you ?I love three things,the sun,the moon,and you.the sun for the day,the moon for the night,and you forever.��去年今日此门中，人面桃花相映红。人面不知何处去，桃花依旧笑春风。��少年不知愁滋味，爱上层楼，爱上层楼，为赋新词强说愁。56321363464.而今识尽愁滋味，欲说还休，欲说还休，却道天凉好个秋。123456，7890，56321267895434。缺月挂疏桐，漏断人初静。谁见幽人独往来，缥缈孤鸿影。惊起却回头，有恨无人省。捡尽寒枝不肯栖，寂寞沙洲冷。";self.font= [UIFontsystemFontOfSize:15]; }returnself;}#pragma mark - 计算高度/**

* 高度 = 每行的asent + 每行的descent + 行数*行间距

* 行间距为指定的数值

* 一行一行绘制，未调整行高（行高不固定）

*/- (void)drawRectWithLineByLine{// 1.创建需要绘制的文字NSMutableAttributedString *attributed = [[NSMutableAttributedString alloc] initWithString:self.text];// 2.设置行距等样式[[selfclass] addGlobalAttributeWithContent:attributed font:self.font];self.textHeight= [[selfclass] textHeightWithText:self.textwidth:CGRectGetWidth(self.bounds) font:self.font];// 3.创建绘制区域，path的高度对绘制有直接影响，如果高度不够，则计算出来的CTLine的数量会少一行或者少多行CGMutablePathRef path = CGPathCreateMutable(); CGPathAddRect(path,NULL, CGRectMake(0,0, CGRectGetWidth(self.bounds),self.textHeight));// 4.根据NSAttributedString生成CTFramesetterRefCTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributed); CTFrameRef ctFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, attributed.length), path,NULL);// 1.获取上下文CGContextRef contextRef = UIGraphicsGetCurrentContext();// 2.转换坐标系CGContextSetTextMatrix(contextRef, CGAffineTransformIdentity); CGContextTranslateCTM(contextRef,0,self.textHeight);// 此处用计算出来的高度CGContextScaleCTM(contextRef,1.0, -1.0);// 重置高度// CGPathAddRect(path, NULL, CGRectMake(0, 0, CGRectGetWidth(self.bounds), self.textHeight));// 一行一行绘制CFArrayRef lines = CTFrameGetLines(ctFrame); CFIndex lineCount = CFArrayGetCount(lines);CGPointlineOrigins[lineCount];// 把ctFrame里每一行的初始坐标写到数组里，注意CoreText的坐标是左下角为原点CTFrameGetLineOrigins(ctFrame, CFRangeMake(0,0), lineOrigins);for(inti =0; i < lineCount; i++){CGPointpoint = lineOrigins[i];NSLog(@"point.y = %f",point.y); }NSLog(@"font.ascender = %f,descender = %f,lineHeight = %f,leading = %f",self.font.ascender,self.font.descender,self.font.lineHeight,self.font.leading);CGFloatframeY =0;for(CFIndex i =0; i < lineCount; i++){// 遍历每一行CTLineCTLineRef line = CFArrayGetValueAtIndex(lines, i);CGFloatlineAscent;CGFloatlineDescent;CGFloatlineLeading;// 行距// 该函数除了会设置好ascent,descent,leading之外，还会返回这行的宽度CTLineGetTypographicBounds(line, &lineAscent, &lineDescent, &lineLeading);NSLog(@"lineAscent = %f",lineAscent);NSLog(@"lineDescent = %f",lineDescent);NSLog(@"lineLeading = %f",lineLeading);CGPointlineOrigin = lineOrigins[i];NSLog(@"i = %ld, lineOrigin = %@",i,NSStringFromCGPoint(lineOrigin));// 微调Y值，需要注意的是CoreText的Y值是在baseLine处，而不是下方的descent。// lineDescent为正数，self.font.descender为负数if(i >0){// 第二行之后需要计算frameY = frameY - kGlobalLineLeading - lineAscent; lineOrigin.y= frameY; }else{// 第一行可直接用frameY = lineOrigin.y; }// 调整坐标CGContextSetTextPosition(contextRef, lineOrigin.x, lineOrigin.y); CTLineDraw(line, contextRef);// 微调frameY = frameY - lineDescent; } CFRelease(path); CFRelease(framesetter); CFRelease(ctFrame);}- (void)drawRect:(CGRect)rect{ [selfdrawRectWithLineByLine];}@end

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.h文件

#import@interfaceMyView:UIView@property(nonatomic,copy)NSString*text;@property(nonatomic,strong)UIFont*font;+ (CGFloat)textHeightWithText:(NSString*)aText width:(CGFloat)aWidth font:(UIFont*)aFont;@end

结果：

3、固定行高

总高度 = 行数*每行的高度

#import"MyView.h"#import// 行距constCGFloatkGlobalLineLeading =5.0;// 在15字体下，比值小于这个计算出来的高度会导致emoji显示不全constCGFloatkPerLineRatio =1.4;@interfaceMyView()@property(nonatomic,assign)CGFloattextHeight;@end@implementationMyView- (instancetype)initWithFrame:(CGRect)frame{self= [superinitWithFrame:frame];if(self) {self.text= @"我自横刀向天笑，去留肝胆两昆仑。--谭嗣同同学你好啊。This is my first CoreText demo,how are you ?I love three things,the sun,the moon,and you.the sun for the day,the moon for the night,and you forever.��去年今日此门中，人面桃花相映红。人面不知何处去，桃花依旧笑春风。��少年不知愁滋味，爱上层楼，爱上层楼，为赋新词强说愁。56321363464.而今识尽愁滋味，欲说还休，欲说还休，却道天凉好个秋。123456，7890，56321267895434。缺月挂疏桐，漏断人初静。谁见幽人独往来，缥缈孤鸿影。惊起却回头，有恨无人省。捡尽寒枝不肯栖，寂寞沙洲冷。";self.font= [UIFontsystemFontOfSize:15]; }returnself;}/**

* 高度 = 每行的固定高度 * 行数

*/+ (CGFloat)textHeightWithText:(NSString*)aText width:(CGFloat)aWidth font:(UIFont*)aFont{ NSMutableAttributedString *content = [[NSMutableAttributedString alloc] initWithString:aText];// 给字符串设置字体行距等样式[selfaddGlobalAttributeWithContent:content font:aFont]; CTFramesetterRef framesetterRef = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)content);// 粗略的高度，该高度不准，仅供参考CGSizesuggestSize = CTFramesetterSuggestFrameSizeWithConstraints(framesetterRef, CFRangeMake(0, content.length),NULL, CGSizeMake(aWidth, MAXFLOAT),NULL);NSLog(@"suggestHeight = %f",suggestSize.height); CGMutablePathRef pathRef = CGPathCreateMutable(); CGPathAddRect(pathRef,NULL, CGRectMake(0,0, aWidth, suggestSize.height)); CTFrameRef frameRef = CTFramesetterCreateFrame(framesetterRef, CFRangeMake(0, content.length), pathRef,NULL); CFArrayRef lines = CTFrameGetLines(frameRef); CFIndex lineCount = CFArrayGetCount(lines);NSLog(@"行数 = %ld",lineCount);// 总高度 = 行数*每行的高度，其中每行的高度为指定的值，不同字体大小不一样CGFloataccurateHeight = lineCount * (aFont.pointSize* kPerLineRatio);CGFloatheight = accurateHeight; CFRelease(pathRef); CFRelease(frameRef);returnheight;}#pragma mark - 工具方法#pragma mark 给字符串添加全局属性，比如行距，字体大小，默认颜色+ (void)addGlobalAttributeWithContent:(NSMutableAttributedString *)aContent font:(UIFont*)aFont{CGFloatlineLeading = kGlobalLineLeading;// 行间距constCFIndex kNumberOfSettings =2;//设置段落格式CTParagraphStyleSetting lineBreakStyle; CTLineBreakMode lineBreakMode = kCTLineBreakByWordWrapping; lineBreakStyle.spec= kCTParagraphStyleSpecifierLineBreakMode; lineBreakStyle.valueSize=sizeof(CTLineBreakMode); lineBreakStyle.value= &lineBreakMode;//设置行距CTParagraphStyleSetting lineSpaceStyle; CTParagraphStyleSpecifier spec; spec = kCTParagraphStyleSpecifierLineSpacingAdjustment; lineSpaceStyle.spec= spec; lineSpaceStyle.valueSize=sizeof(CGFloat); lineSpaceStyle.value= &lineLeading;// 结构体数组CTParagraphStyleSetting theSettings[kNumberOfSettings] = { lineBreakStyle, lineSpaceStyle, }; CTParagraphStyleRef theParagraphRef = CTParagraphStyleCreate(theSettings, kNumberOfSettings);// 将设置的行距应用于整段文字[aContent addAttribute:NSParagraphStyleAttributeName value:(__bridgeid)(theParagraphRef) range:NSMakeRange(0, aContent.length)]; CFStringRef fontName = (__bridge CFStringRef)aFont.fontName; CTFontRef fontRef = CTFontCreateWithName(fontName, aFont.pointSize,NULL);// 将字体大小应用于整段文字[aContent addAttribute:NSFontAttributeName value:(__bridgeid)fontRef range:NSMakeRange(0, aContent.length)];// 给整段文字添加默认颜色[aContent addAttribute:NSForegroundColorAttributeName value:[UIColorblackColor] range:NSMakeRange(0, aContent.length)];// 内存管理CFRelease(theParagraphRef); CFRelease(fontRef);}#pragma mark - 一行一行绘制，行高确定，行与行之间对齐- (void)drawRectWithLineByLineAlignment{// 1.创建需要绘制的文字NSMutableAttributedString *attributed = [[NSMutableAttributedString alloc] initWithString:self.text];// 2.设置行距等样式[[selfclass] addGlobalAttributeWithContent:attributed font:self.font];self.textHeight= [[selfclass] textHeightWithText:self.textwidth:CGRectGetWidth(self.bounds) font:self.font];// 3.创建绘制区域，path的高度对绘制有直接影响，如果高度不够，则计算出来的CTLine的数量会少一行或者少多行CGMutablePathRef path = CGPathCreateMutable(); CGPathAddRect(path,NULL, CGRectMake(0,0, CGRectGetWidth(self.bounds),self.textHeight*2));// 4.根据NSAttributedString生成CTFramesetterRefCTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributed); CTFrameRef ctFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, attributed.length), path,NULL);// 获取上下文CGContextRef contextRef = UIGraphicsGetCurrentContext();// 转换坐标系CGContextSetTextMatrix(contextRef, CGAffineTransformIdentity); CGContextTranslateCTM(contextRef,0,self.textHeight);// 此处用计算出来的高度CGContextScaleCTM(contextRef,1.0, -1.0);// 一行一行绘制CFArrayRef lines = CTFrameGetLines(ctFrame); CFIndex lineCount = CFArrayGetCount(lines);CGPointlineOrigins[lineCount];// 把ctFrame里每一行的初始坐标写到数组里，注意CoreText的坐标是左下角为原点CTFrameGetLineOrigins(ctFrame, CFRangeMake(0,0), lineOrigins);for(inti =0; i < lineCount; i++) {CGPointpoint = lineOrigins[i];NSLog(@"point.y = %f",point.y); }NSLog(@"font.ascender = %f,descender = %f,lineHeight = %f,leading = %f",self.font.ascender,self.font.descender,self.font.lineHeight,self.font.leading);CGFloatframeY =0;NSLog(@"self.textHeight = %f,lineHeight = %f",self.textHeight,self.font.pointSize* kPerLineRatio);for(CFIndex i =0; i < lineCount; i++){// 遍历每一行CTLineCTLineRef line = CFArrayGetValueAtIndex(lines, i);CGFloatlineAscent;CGFloatlineDescent;CGFloatlineLeading;// 行距// 该函数除了会设置好ascent,descent,leading之外，还会返回这行的宽度CTLineGetTypographicBounds(line, &lineAscent, &lineDescent, &lineLeading);NSLog(@"lineAscent = %f",lineAscent);NSLog(@"lineDescent = %f",lineDescent);NSLog(@"lineLeading = %f",lineLeading);CGPointlineOrigin = lineOrigins[i];NSLog(@"i = %ld, lineOrigin = %@",i,NSStringFromCGPoint(lineOrigin));// 微调Y值，需要注意的是CoreText的Y值是在baseLine处，而不是下方的descent。CGFloatlineHeight =self.font.pointSize* kPerLineRatio; frameY =self.textHeight- (i +1)*lineHeight -self.font.descender;NSLog(@"frameY = %f",frameY); lineOrigin.y= frameY;// 调整坐标CGContextSetTextPosition(contextRef, lineOrigin.x, lineOrigin.y); CTLineDraw(line, contextRef); } CFRelease(path); CFRelease(framesetter); CFRelease(ctFrame);}- (void)drawRect:(CGRect)rect{ [selfdrawRectWithLineByLineAlignment];}@end