iOS 項(xiàng)目小結(jié)

1.iOS中的round辜窑、ceil、floor函數(shù)略解

round如果參數(shù)是小數(shù)寨躁，則求本身的四舍五入.ceil如果參數(shù)是小數(shù)穆碎，則求最小的整數(shù)但不小于本身.floor如果參數(shù)是小數(shù)，則求最大的整數(shù)但不大于本身.

Example:如何值是3.4的話职恳，則

-- round 3.000000

-- ceil 4.000000

-- floor 3.00000

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CoreText（四）：行 CTLineRef

標(biāo)簽：字體 coretext

2016-09-08 18:14241人閱讀評論(0)收藏舉報(bào)

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iOS連載（8）

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目錄(?)[+]

一色徘、字符(Character)和字形(Glyphs)

排版過程中一個重要的步驟就是從字符到字形的轉(zhuǎn)換恭金，字符表示信息本身，而字形是它的圖形表現(xiàn)形式褂策。字符一般就是指某種編碼横腿，如Unicode編碼，而字形則是這些編碼對應(yīng)的圖片斤寂。但是他們之間不是一一對應(yīng)關(guān)系耿焊，同個字符的不同字體族，不同字體大小扬蕊，不同字體樣式都對應(yīng)了不同的字形艇拍。而由于連寫(Ligatures)的存在桑包，多個字符也會存在對應(yīng)一個字形的情況姚垃。

下面就來詳情看看字形的各個參數(shù)也就是所謂的字形度量Glyph Metrics

（1）函筋、邊界框 bbox(bounding box)

這是一個假想的框子，它盡可能緊密的裝入字形再愈。

（2）榜苫、基線(baseline)

一條假想的線,一行上的字形都以此線作為上下位置的參考，在這條線的左側(cè)存在一個點(diǎn)叫做基線的原點(diǎn)翎冲，

（3）垂睬、上行高度(ascent)

從原點(diǎn)到字體中最高（這里的高深都是以基線為參照線的）的字形的頂部的距離，ascent是一個正值

（4）抗悍、下行高度(descent)

從原點(diǎn)到字體中最深的字形底部的距離驹饺，descent是一個負(fù)值（比如一個字體原點(diǎn)到最深的字形的底部的距離為2，那么descent就為-2）

（5）缴渊、行距(line gap)

line gap也可以稱作leading（其實(shí)準(zhǔn)確點(diǎn)講應(yīng)該叫做External leading）,行高line Height則可以通過 ascent + |descent| + linegap 來計(jì)算赏壹。

（6）、字間距(Kerning)

字與字之間的距離衔沼，為了排版的美觀蝌借，并不是所有的字形之間的距離都是一致的，但是這個基本步影響到我們的文字排版指蚁。

（7）菩佑、基礎(chǔ)原點(diǎn)(Origin)

基線上最左側(cè)的點(diǎn)。

紅框高度既為當(dāng)前行的行高凝化，綠線為baseline稍坯，綠色到紅框上部分為當(dāng)前行的最大Ascent，綠線到黃線為當(dāng)前行的最大Desent搓劫，而黃框的高即為行間距劣光。由此可以得出：lineHeight = Ascent + |Decent| + Leading袜蚕。

二、坐標(biāo)系

傳統(tǒng)的Mac中的坐標(biāo)系的原點(diǎn)在左下角绢涡，比如NSView默認(rèn)的坐標(biāo)系，原點(diǎn)就在左下角遣疯。但Mac中有些View為了其實(shí)現(xiàn)的便捷將原點(diǎn)變換到左上角雄可，像NSTableView的坐標(biāo)系坐標(biāo)原點(diǎn)就在左上角。

iOSUIKit中缠犀，UIView是以左上角為原點(diǎn)数苫，而Core Text一開始的定位是使用與桌面應(yīng)用的排版系統(tǒng)，桌面應(yīng)用的坐標(biāo)系是以左下角為原點(diǎn)辨液，即Core Text在繪制的時(shí)候也是參照左下角為原點(diǎn)進(jìn)行繪制的虐急，所以需要對當(dāng)前的坐標(biāo)系進(jìn)行處理。

實(shí)際上滔迈，Core Graphic 中的context也是以左下角為原點(diǎn)的止吁，但是為什么我們用Core Graphic

繪制一些簡單的圖形的時(shí)候不需要對坐標(biāo)系進(jìn)行處理呢，是因?yàn)橥ㄟ^這個方法UIGraphicsGetCurrentContext()來獲得的當(dāng)前context是已經(jīng)被處理過的了燎悍，用下面方法可以查看指定的上下文的當(dāng)前圖形狀態(tài)變換矩陣敬惦。

方法一

//因?yàn)镃ore Text要配合Core Graphic 配合使用的，如Core Graphic一樣谈山，繪圖的時(shí)候需要獲得當(dāng)前的上下文進(jìn)行繪制CGContextRef context = UIGraphicsGetCurrentContext();NSLog(@"當(dāng)前context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));//翻轉(zhuǎn)當(dāng)前的坐標(biāo)系（因?yàn)閷τ诘讓永L制引擎來說俄删，屏幕左下角為（0，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);//設(shè)置字形變換矩陣為CGAffineTransformIdentity奏路，也就是說每一個字形都不做圖形變換CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);CGContextConcatCTM(context, flipVertical);//將當(dāng)前context的坐標(biāo)系進(jìn)行flipNSLog(@"翻轉(zhuǎn)后context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));

打印結(jié)果為：

當(dāng)前context的變換矩陣[2, 0, 0, -2, 0, 800]翻轉(zhuǎn)后context的變換矩陣[2, 0, 0, 2, 0, 0]

方法二

//因?yàn)镃ore Text要配合Core Graphic 配合使用的畴椰，如Core Graphic一樣，繪圖的時(shí)候需要獲得當(dāng)前的上下文進(jìn)行繪制CGContextRefcontext= UIGraphicsGetCurrentContext();NSLog(@"當(dāng)前context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));//翻轉(zhuǎn)當(dāng)前的坐標(biāo)系（因?yàn)閷τ诘讓永L制引擎來說鸽粉，屏幕左下角為（0斜脂，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);CGContextTranslateCTM(context,0, self.bounds.size.height);CGContextScaleCTM(context,1.0, -1.0);NSLog(@"翻轉(zhuǎn)后context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));

打印：

當(dāng)前context的變換矩陣[2, 0, 0, -2, 0, 800]翻轉(zhuǎn)后context的變換矩陣[2, 0, -0, 2, 0, 0]

可以發(fā)現(xiàn)變換矩陣與CGAffineTransformIdentity的值[1, 0, 0, 1, 0,

0]是不相同的潜叛，并且與設(shè)備是否為Retina屏和設(shè)備尺寸相關(guān)秽褒。他的作用是將上下文空間坐標(biāo)系進(jìn)行翻轉(zhuǎn)，并使原來的左下角原點(diǎn)變成左上角是原點(diǎn)威兜，并將向上為正y軸變?yōu)橄蛳聻檎齳軸销斟。

所以在使用drawRect的時(shí)候，當(dāng)前的context已經(jīng)被做了一次翻轉(zhuǎn)椒舵，如果不對當(dāng)前的坐標(biāo)系進(jìn)行處理蚂踊，會發(fā)現(xiàn)，繪制出來的文字是鏡像上下顛倒的笔宿。所以在UIView的drawRect方法中的context上進(jìn)行Core

Text繪制之前需要對context進(jìn)行一次Flip犁钟。

三棱诱、主要函數(shù)

1、傳入CTFrame涝动，返回一個裝有多個CTLine對象的數(shù)組迈勋。

CFArrayRefCTFrameGetLines(

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

2、獲取數(shù)組中的元素個數(shù)

CFIndexCFArrayGetCount(CFArrayRef theArray);

3醋粟、獲取數(shù)組中第idx個元素

constvoid*CFArrayGetValueAtIndex(CFArrayRef theArray, CFIndex idx);

4靡菇、獲取所有CTLineRef的基礎(chǔ)原點(diǎn)，傳入CTFrame米愿，CFRange厦凤，和一個CGPoint的結(jié)構(gòu)體數(shù)組指針，該函數(shù)會把每一個CTLine的origin坐標(biāo)寫到數(shù)組里育苟。

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

5较鼓、獲取CTLine中文字在整段文字中的Range

CFRangeCTLineGetStringRange(

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

6、獲取CTLine中的CTRun的數(shù)組

CFArrayRefCTLineGetGlyphRuns(

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

7违柏、獲取CTRun在整段文字中的Range

CFRangeCTRunGetStringRange(

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

8博烂、獲取點(diǎn)擊處position文字在整段文字中的index

CFIndexCTLineGetStringIndexForPosition(

CTLineRef line,

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

9、獲取整段文字中charIndex位置的字符相對line的原點(diǎn)的x值

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

10勇垛、獲取數(shù)組中字形個個數(shù)

CFIndexCTLineGetGlyphCount(

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

11脖母、設(shè)置CoreText繪制前的坐標(biāo)。設(shè)置基線位置

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

12闲孤、繪制CTLine谆级。

voidCTLineDraw(

CTLineRef line,

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

13、獲取CTLine的上行高度讼积，下行高度肥照，行距

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

14、設(shè)置當(dāng)前文本矩陣

CG_EXTERN voidCGContextSetTextMatrix(CGContextRef __nullable c,

CGAffineTransform t)CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

15勤众、獲取一行文字的范圍舆绎，

就是指把這一行文字點(diǎn)有的像素矩陣作為一個image圖片，來得到整個矩形區(qū)域们颜。相對于每一行基線原點(diǎn)的偏移量和寬高（例如：{{1.2吕朵，

-2.57227}, {208.025,

19.2523}}，就是相對于本身的基線原點(diǎn)向右偏移1.2個單位窥突，向下偏移2.57227個單位努溃，后面是寬高）

CGRectCTLineGetImageBounds(

CTLineRef line,

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

例如：

//獲取frame中CTLineRef數(shù)組CFArrayRef Lines = CTFrameGetLines(frame);//獲取數(shù)組Lines中的個數(shù)CFIndex lineCount = CFArrayGetCount(Lines);//獲取數(shù)組中第一個CTLineRefCTLineRef lineRef = CFArrayGetValueAtIndex(Lines,0);//獲取lineRef中CTRunRef數(shù)組CFArrayRef runs = CTLineGetGlyphRuns(lineRef);//獲取CTLineRef中字形個數(shù)CFIndex rus = CTLineGetGlyphCount(lineRef);//獲取數(shù)組runs中的個數(shù)CFIndex runCount = CFArrayGetCount(runs);NSLog(@"lines =%ldruns =%ldrus =%ld",lineCount,runCount,rus);

打印：

lines=7? runs = 5 rus = 37

四阻问、舉例

1梧税、繪框

- (void)drawRect:(CGRect)rect{// 步驟1：得到當(dāng)前用于繪制畫布的上下文，用于后續(xù)將內(nèi)容繪制在畫布上// 因?yàn)镃ore Text要配合Core Graphic 配合使用的，如Core Graphic一樣第队，繪圖的時(shí)候需要獲得當(dāng)前的上下文進(jìn)行繪制CGContextRef context = UIGraphicsGetCurrentContext();NSLog(@"當(dāng)前context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步驟2：翻轉(zhuǎn)當(dāng)前的坐標(biāo)系（因?yàn)閷τ诘讓永L制引擎來說哮塞，屏幕左下角為（0，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);//設(shè)置字形變換矩陣為CGAffineTransformIdentity凳谦，也就是說每一個字形都不做圖形變換CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);? ? CGContextConcatCTM(context, flipVertical);//將當(dāng)前context的坐標(biāo)系進(jìn)行flipNSLog(@"翻轉(zhuǎn)后context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步驟3：創(chuàng)建繪制區(qū)域CGMutablePathRef path = CGPathCreateMutable();? ? CGPathAddRect(path,NULL,self.bounds);// 步驟4：創(chuàng)建需要繪制的文字與計(jì)算需要繪制的區(qū)域NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:@"iOS程序在啟動時(shí)會創(chuàng)建一個主線程忆畅，而在一個線程只能執(zhí)行一件事情，如果在主線程執(zhí)行某些耗時(shí)操作尸执，例如加載網(wǎng)絡(luò)圖片邻眷，下載資源文件等會阻塞主線程（導(dǎo)致界面卡死，無法交互）剔交，所以就需要使用多線程技術(shù)來避免這類情況。iOS中有三種多線程技術(shù) NSThread改衩，NSOperation岖常，GCD，這三種技術(shù)是隨著IOS發(fā)展引入的葫督，抽象層次由低到高竭鞍，使用也越來越簡單。"];// 步驟5：根據(jù)AttributedString生成CTFramesetterRefCTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString);? ? CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, [attrString length]), path,NULL);//獲取frame中CTLineRef數(shù)組CFArrayRef Lines = CTFrameGetLines(frame);//獲取數(shù)組Lines中的個數(shù)CFIndex lineCount = CFArrayGetCount(Lines);//獲取基線原點(diǎn)CGPointorigins[lineCount];? ? CTFrameGetLineOrigins(frame, CFRangeMake(0,0), origins);for(CFIndex i =0; i < lineCount; i ++) {? ? ? ? CTLineRef line = CFArrayGetValueAtIndex(Lines, i);//相對于每一行基線原點(diǎn)的偏移量和寬高（例如：{{1.2橄镜， -2.57227}, {208.025, 19.2523}}偎快，就是相對于本身的基線原點(diǎn)向右偏移1.2個單位，向下偏移2.57227個單位洽胶，后面是寬高）CGRectlineBounds = CTLineGetImageBounds((CTLineRef)line, context);NSLog(@"lineBounds = %@",NSStringFromCGRect(lineBounds));NSLog(@"point = %@",NSStringFromCGPoint(origins[i]));//每一行的起始點(diǎn)（相對于context）加上相對于本身基線原點(diǎn)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);? ? }// 步驟6：進(jìn)行繪制CTFrameDraw(frame, context);// 步驟7.內(nèi)存管理CFRelease(frame);? ? CFRelease(path);? ? CFRelease(frameSetter);}

打由辜小：

當(dāng)前context的變換矩陣 [2,0,0,-2,0,800]翻轉(zhuǎn)后context的變換矩陣 [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、單行繪制

- (void)drawRect:(CGRect)rect{// 步驟1：得到當(dāng)前用于繪制畫布的上下文姊氓，用于后續(xù)將內(nèi)容繪制在畫布上// 因?yàn)镃ore Text要配合Core Graphic 配合使用的丐怯，如Core Graphic一樣，繪圖的時(shí)候需要獲得當(dāng)前的上下文進(jìn)行繪制CGContextRef context = UIGraphicsGetCurrentContext();NSLog(@"當(dāng)前context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步驟2：翻轉(zhuǎn)當(dāng)前的坐標(biāo)系（因?yàn)閷τ诘讓永L制引擎來說翔横，屏幕左下角為（0读跷，0））CGContextSetTextMatrix(context, CGAffineTransformIdentity);//設(shè)置字形變換矩陣為CGAffineTransformIdentity，也就是說每一個字形都不做圖形變換CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);? ? CGContextConcatCTM(context, flipVertical);//將當(dāng)前context的坐標(biāo)系進(jìn)行flipNSLog(@"翻轉(zhuǎn)后context的變換矩陣 %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));// 步驟3：創(chuàng)建繪制區(qū)域CGMutablePathRef path = CGPathCreateMutable();? ? CGPathAddRect(path,NULL,self.bounds);// 步驟4：創(chuàng)建需要繪制的文字與計(jì)算需要繪制的區(qū)域NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:@"門梁真可怕當(dāng)中英文混合之后禾唁，??????????會出現(xiàn)行高不統(tǒng)一的情況效览，現(xiàn)在在繪制的時(shí)候根據(jù)字體的descender來偏移繪制，對齊baseline荡短。??????????同時(shí)點(diǎn)擊鏈接的時(shí)候會調(diào)用drawRect: 造成繪制異常丐枉，所以將setNeedsDisplay注釋，如需刷新肢预，請手動調(diào)用矛洞。帶上emoji以供測試????????????????????"];? ? CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"),20,NULL);? ? [attrString addAttribute:(id)kCTFontAttributeName value:(__bridgeid)font range:NSMakeRange(0, attrString.length)];// 步驟5：根據(jù)AttributedString生成CTFramesetterRefCTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString);? ? CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, [attrString length]), path,NULL);//獲取frame中CTLineRef數(shù)組CFArrayRef Lines = CTFrameGetLines(frame);//獲取數(shù)組Lines中的個數(shù)CFIndex lineCount = CFArrayGetCount(Lines);//獲取基線原點(diǎn)CGPointorigins[lineCount];? ? CTFrameGetLineOrigins(frame, CFRangeMake(0,0), origins);for(CFIndex i =0; i < lineCount; i ++) {? ? ? ? CTLineRef line = CFArrayGetValueAtIndex(Lines, i);//遍歷每一行CTLineCGFloatlineAscent;CGFloatlineDescent;CGFloatlineLeading;// 行距// 該函數(shù)除了會設(shè)置好ascent,descent,leading之外，還會返回這行的寬度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改動前：%@",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改動后 = %@",NSStringFromCGRect(lineBounds));//填充CGContextSetLineWidth(context,1.0);? ? ? ? CGContextAddRect(context,lineBounds);? ? ? ? CGContextSetStrokeColorWithColor(context, [[UIColorredColor] CGColor]);? ? ? ? CGContextStrokeRect(context, lineBounds);? ? ? ? CTLineDraw(line, context);//繪制原點(diǎn)為左下角}// 步驟6：進(jìn)行繪制//? ? CTFrameDraw(frame, context);// 步驟7.內(nèi)存管理CFRelease(frame);? ? CFRelease(path);? ? CFRelease(frameSetter);}

打印數(shù)據(jù)：

當(dāng)前context的變換矩陣 [2,0,0, -2,0,800]翻轉(zhuǎn)后context的變換矩陣 [2,0,0,2,0,0]lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 378}lineBounds改動前：{{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改動后 ={{1.98, 363.19023437499999},{328.34421874999998, 22}}lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 349}lineBounds改動前：{{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改動后 ={{0.5, 334.19023437499999},{367.41999999999996, 22}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 321}lineBounds改動前：{{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改動后 ={{0.83999999999999997, 307.65523437499996},{368.16703124999998, 18.66}}lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 292}lineBounds改動前：{{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改動后 ={{0.70000000000000007, 277.19023437499999},{365.81625000000003, 22}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 264}lineBounds改動前：{{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改動后 ={{0.76000000000000001, 250.65523437499999},{353.68367187500002, 18.620000000000001}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 236}lineBounds改動前：{{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改動后 ={{1.6799999999999999, 220.47929687499999},{363.27226562499999, 20.775937499999998}}lineAscent =21.200000lineDescent =6.800000lineLeading =0.000000point ={0, 208}lineBounds改動前：{{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改動后 ={{0.68000000000000005, 192.47929687499999},{328.44562499999995, 20.915937499999998}}lineAscent =22.000000lineDescent =6.875000lineLeading =0.000000point ={0, 179}lineBounds改動前：{{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改動后 ={{0.5, 164.19023437499999},{229, 22}}

3、固定行間距

行高=每行的asent + 每行的descent + 行數(shù)*行間距

#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= @"我自橫刀向天笑沼本，去留肝膽兩昆侖噩峦。--譚嗣同同學(xué)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.??????????????去年今日此門中抽兆，人面桃花相映紅识补。人面不知何處去，桃花依舊笑春風(fēng)辫红。??????????????少年不知愁滋味凭涂，愛上層樓，愛上層樓贴妻，為賦新詞強(qiáng)說愁切油。56321363464.而今識盡愁滋味，欲說還休名惩，欲說還休澎胡，卻道天涼好個秋。123456娩鹉，7890攻谁，56321267895434。缺月掛疏桐弯予，漏斷人初靜戚宦。誰見幽人獨(dú)往來，縹緲孤鴻影锈嫩。驚起卻回頭受楼，有恨無人省。撿盡寒枝不肯棲祠挫，寂寞沙洲冷那槽。";self.font= [UIFontsystemFontOfSize:15];? ? }returnself;}#pragma mark - 計(jì)算高度/**

*? 高度 = 每行的asent + 每行的descent + 行數(shù)*行間距

*? 行間距為指定的數(shù)值

*? 一行一行繪制慌植，未調(diào)整行高（行高不固定）

*/- (void)drawRectWithLineByLine{// 1.創(chuàng)建需要繪制的文字NSMutableAttributedString *attributed = [[NSMutableAttributedString alloc] initWithString:self.text];// 2.設(shè)置行距等樣式[[selfclass] addGlobalAttributeWithContent:attributed font:self.font];self.textHeight= [[selfclass] textHeightWithText:self.textwidth:CGRectGetWidth(self.bounds) font:self.font];// 3.創(chuàng)建繪制區(qū)域甚牲，path的高度對繪制有直接影響，如果高度不夠蝶柿，則計(jì)算出來的CTLine的數(shù)量會少一行或者少多行CGMutablePathRef path = CGPathCreateMutable();? ? CGPathAddRect(path,NULL, CGRectMake(0,0, CGRectGetWidth(self.bounds),self.textHeight));// 4.根據(jù)NSAttributedString生成CTFramesetterRefCTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributed);? ? CTFrameRef ctFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, attributed.length), path,NULL);// 1.獲取上下文CGContextRef contextRef = UIGraphicsGetCurrentContext();// 2.轉(zhuǎn)換坐標(biāo)系CGContextSetTextMatrix(contextRef, CGAffineTransformIdentity);? ? CGContextTranslateCTM(contextRef,0,self.textHeight);// 此處用計(jì)算出來的高度CGContextScaleCTM(contextRef,1.0, -1.0);// 重置高度//? ? CGPathAddRect(path, NULL, CGRectMake(0, 0, CGRectGetWidth(self.bounds), self.textHeight));// 一行一行繪制CFArrayRef lines = CTFrameGetLines(ctFrame);? ? CFIndex lineCount = CFArrayGetCount(lines);CGPointlineOrigins[lineCount];// 把ctFrame里每一行的初始坐標(biāo)寫到數(shù)組里丈钙，注意CoreText的坐標(biāo)是左下角為原點(diǎn)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++){// 遍歷每一行CTLineCTLineRef line = CFArrayGetValueAtIndex(lines, i);CGFloatlineAscent;CGFloatlineDescent;CGFloatlineLeading;// 行距// 該函數(shù)除了會設(shè)置好ascent,descent,leading之外，還會返回這行的寬度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));// 微調(diào)Y值交汤，需要注意的是CoreText的Y值是在baseLine處雏赦，而不是下方的descent劫笙。// lineDescent為正數(shù)，self.font.descender為負(fù)數(shù)if(i >0){// 第二行之后需要計(jì)算frameY = frameY - kGlobalLineLeading - lineAscent;? ? ? ? ? ? lineOrigin.y= frameY;? ? ? ? }else{// 第一行可直接用frameY = lineOrigin.y;? ? ? ? }// 調(diào)整坐標(biāo)CGContextSetTextPosition(contextRef, lineOrigin.x, lineOrigin.y);? ? ? ? CTLineDraw(line, contextRef);// 微調(diào)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

結(jié)果：

3星岗、固定行高

總高度 = 行數(shù)*每行的高度

#import"MyView.h"#import// 行距constCGFloatkGlobalLineLeading =5.0;// 在15字體下填大，比值小于這個計(jì)算出來的高度會導(dǎo)致emoji顯示不全constCGFloatkPerLineRatio =1.4;@interfaceMyView()@property(nonatomic,assign)CGFloattextHeight;@end@implementationMyView- (instancetype)initWithFrame:(CGRect)frame{self= [superinitWithFrame:frame];if(self) {self.text= @"我自橫刀向天笑，去留肝膽兩昆侖俏橘。--譚嗣同同學(xué)你好啊允华。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.??????????????去年今日此門中，人面桃花相映紅寥掐。人面不知何處去靴寂，桃花依舊笑春風(fēng)。??????????????少年不知愁滋味召耘，愛上層樓百炬，愛上層樓，為賦新詞強(qiáng)說愁污它。56321363464.而今識盡愁滋味收壕，欲說還休，欲說還休轨蛤，卻道天涼好個秋。123456虫埂，7890祥山，56321267895434。缺月掛疏桐掉伏，漏斷人初靜缝呕。誰見幽人獨(dú)往來，縹緲孤鴻影斧散。驚起卻回頭供常，有恨無人省。撿盡寒枝不肯棲鸡捐，寂寞沙洲冷栈暇。";self.font= [UIFontsystemFontOfSize:15];? ? }returnself;}/**

*? 高度 = 每行的固定高度 * 行數(shù)

*/+ (CGFloat)textHeightWithText:(NSString*)aText width:(CGFloat)aWidth font:(UIFont*)aFont{? ? NSMutableAttributedString *content = [[NSMutableAttributedString alloc] initWithString:aText];// 給字符串設(shè)置字體行距等樣式[selfaddGlobalAttributeWithContent:content font:aFont];? ? CTFramesetterRef framesetterRef = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)content);// 粗略的高度，該高度不準(zhǔn)箍镜，僅供參考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(@"行數(shù) = %ld",lineCount);// 總高度 = 行數(shù)*每行的高度源祈，其中每行的高度為指定的值，不同字體大小不一樣CGFloataccurateHeight = lineCount * (aFont.pointSize* kPerLineRatio);CGFloatheight = accurateHeight;? ? CFRelease(pathRef);? ? CFRelease(frameRef);returnheight;}#pragma mark - 工具方法#pragma mark 給字符串添加全局屬性色迂，比如行距香缺，字體大小，默認(rèn)顏色+ (void)addGlobalAttributeWithContent:(NSMutableAttributedString *)aContent font:(UIFont*)aFont{CGFloatlineLeading = kGlobalLineLeading;// 行間距constCFIndex kNumberOfSettings =2;//設(shè)置段落格式CTParagraphStyleSetting lineBreakStyle;? ? CTLineBreakMode lineBreakMode = kCTLineBreakByWordWrapping;? ? lineBreakStyle.spec= kCTParagraphStyleSpecifierLineBreakMode;? ? lineBreakStyle.valueSize=sizeof(CTLineBreakMode);? ? lineBreakStyle.value= &lineBreakMode;//設(shè)置行距CTParagraphStyleSetting lineSpaceStyle;? ? CTParagraphStyleSpecifier spec;? ? spec = kCTParagraphStyleSpecifierLineSpacingAdjustment;? ? lineSpaceStyle.spec= spec;? ? lineSpaceStyle.valueSize=sizeof(CGFloat);? ? lineSpaceStyle.value= &lineLeading;// 結(jié)構(gòu)體數(shù)組CTParagraphStyleSetting theSettings[kNumberOfSettings] = {? ? ? ? lineBreakStyle,? ? ? ? lineSpaceStyle,? ? };? ? CTParagraphStyleRef theParagraphRef = CTParagraphStyleCreate(theSettings, kNumberOfSettings);// 將設(shè)置的行距應(yīng)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);// 將字體大小應(yīng)用于整段文字[aContent addAttribute:NSFontAttributeName value:(__bridgeid)fontRef range:NSMakeRange(0, aContent.length)];// 給整段文字添加默認(rèn)顏色[aContent addAttribute:NSForegroundColorAttributeName value:[UIColorblackColor] range:NSMakeRange(0, aContent.length)];// 內(nèi)存管理CFRelease(theParagraphRef);? ? CFRelease(fontRef);}#pragma mark - 一行一行繪制歇僧，行高確定图张，行與行之間對齊- (void)drawRectWithLineByLineAlignment{// 1.創(chuàng)建需要繪制的文字NSMutableAttributedString *attributed = [[NSMutableAttributedString alloc] initWithString:self.text];// 2.設(shè)置行距等樣式[[selfclass] addGlobalAttributeWithContent:attributed font:self.font];self.textHeight= [[selfclass] textHeightWithText:self.textwidth:CGRectGetWidth(self.bounds) font:self.font];// 3.創(chuàng)建繪制區(qū)域，path的高度對繪制有直接影響，如果高度不夠祸轮，則計(jì)算出來的CTLine的數(shù)量會少一行或者少多行CGMutablePathRef path = CGPathCreateMutable();? ? CGPathAddRect(path,NULL, CGRectMake(0,0, CGRectGetWidth(self.bounds),self.textHeight*2));// 4.根據(jù)NSAttributedString生成CTFramesetterRefCTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributed);? ? CTFrameRef ctFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, attributed.length), path,NULL);// 獲取上下文CGContextRef contextRef = UIGraphicsGetCurrentContext();// 轉(zhuǎn)換坐標(biāo)系CGContextSetTextMatrix(contextRef, CGAffineTransformIdentity);? ? CGContextTranslateCTM(contextRef,0,self.textHeight);// 此處用計(jì)算出來的高度CGContextScaleCTM(contextRef,1.0, -1.0);// 一行一行繪制CFArrayRef lines = CTFrameGetLines(ctFrame);? ? CFIndex lineCount = CFArrayGetCount(lines);CGPointlineOrigins[lineCount];// 把ctFrame里每一行的初始坐標(biāo)寫到數(shù)組里兽埃，注意CoreText的坐標(biāo)是左下角為原點(diǎn)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++){// 遍歷每一行CTLineCTLineRef line = CFArrayGetValueAtIndex(lines, i);CGFloatlineAscent;CGFloatlineDescent;CGFloatlineLeading;// 行距// 該函數(shù)除了會設(shè)置好ascent,descent,leading之外，還會返回這行的寬度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));// 微調(diào)Y值倔撞，需要注意的是CoreText的Y值是在baseLine處讲仰，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;// 調(diào)整坐標(biāo)CGContextSetTextPosition(contextRef, lineOrigin.x, lineOrigin.y);? ? ? ? CTLineDraw(line, contextRef);? ? }? ? CFRelease(path);? ? CFRelease(framesetter);? ? CFRelease(ctFrame);}- (void)drawRect:(CGRect)rect{? ? [selfdrawRectWithLineByLineAlignment];}@end