ios之coretext - 润新知

ios之coretext
API接口文档。

https://developer.apple.com/library/mac/#documentation/Carbon/Reference/CoreText_Framework_Ref/_index.html

CoreText 框架中最常用的几个类：
先来了解一下该框架的整体视窗组合图：

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。

字体的基本知识：

字体(Font):是一系列字号、样式和磅值相同的字符(例如:10磅黑体Palatino)。现多被视为字样的同义词

字面(Face):是所有字号的磅值和格式的综合

字体集(Font family):是一组相关字体(例如:Franklin family包括Franklin Gothic、Fran-klinHeavy和Franklin Compressed)

磅值(Weight):用于描述字体粗度。典型的磅值,从最粗到最细,有极细、细、book、中等、半粗、粗、较粗、极粗

样式(Style):字形有三种形式:Roman type是直体;oblique type是斜体;utakuc type是斜体兼曲线(比Roman type更像书法体)。

x高度(X height):指小写字母的平均高度(以x为基准)。磅值相同的两字母,x高度越大的字母看起来比x高度小的字母要大

Cap高度(Cap height):与x高度相似。指大写字母的平均高度(以C为基准)

下行字母(Descender):例如在字母q中,基线以下的字母部分叫下伸部分

上行字母(Ascender):x高度以上的部分(比如字母b)叫做上伸部分

基线(Baseline):通常在x、v、b、m下的那条线

描边(Stroke):组成字符的线或曲线。可以加粗或改变字符形状

衬线(Serif):用来使字符更可视的一条水平线。如字母左上角和下部的水平线。

无衬线(Sans Serif):可以让排字员不使用衬线装饰。

方形字(Block):这种字体的笔画使字符看起来比无衬线字更显眼,但还不到常见的衬线字的程度。例如Lubalin Graph就是方形字,这种字看起来好像是木头块刻的一样

手写体脚本(Calligraphic script):是一种仿效手写体的字体。例如Murray Hill或者Fraktur字体

艺术字(Decorative):像绘画般的字体

Pi符号(Pisymbol):非标准的字母数字字符的特殊符号。例如Wingdings和Mathematical Pi

连写(Ligature):是一系列连写字母如fi、fl、ffi或ffl。由于字些字母形状的原因经常被连写,故排字员已习惯将它们连写。

字符属性名称：
```
const CFStringRef kCTCharacterShapeAttributeName;              
```
```
//字体形状属性  必须是CFNumberRef对象默认为0，非0则对应相应的字符形状定义，如1表示传统字符形状
```
```
const CFStringRef kCTFontAttributeName;                        
```
```
//字体属性   必须是CTFont对象
const CFStringRef kCTKernAttributeName;                        
```
```
//字符间隔属性 必须是CFNumberRef对象
const CFStringRef kCTLigatureAttributeName;                 
```
```
//设置是否使用连字属性，设置为0，表示不使用连字属性。标准的英文连字有FI,FL.默认值为1，既是使用标准连字。也就是当搜索到f时候，会把fl当成一个文字。必须是CFNumberRef 默认为1,可取0,1,2
const CFStringRef kCTForegroundColorAttributeName;             
```
```
//字体颜色属性  必须是CGColor对象，默认为black
const CFStringRef kCTForegroundColorFromContextAttributeName; 
```
```
 //上下文的字体颜色属性 必须为CFBooleanRef 默认为False,
const CFStringRef kCTParagraphStyleAttributeName;              
```
```
//段落样式属性 必须是CTParagraphStyle对象 默认为NIL
const CFStringRef kCTStrokeWidthAttributeName;              
```
```
//笔画线条宽度 必须是CFNumberRef对象，默为0.0f，标准为3.0f
const CFStringRef kCTStrokeColorAttributeName;              
```
```
//笔画的颜色属性 必须是CGColorRef 对象，默认为前景色
const CFStringRef kCTSuperscriptAttributeName;              
```
```
//设置字体的上下标属性 必须是CFNumberRef对象 默认为0,可为-1为下标,1为上标，需要字体支持才行。如排列组合的样式Cn1
const CFStringRef kCTUnderlineColorAttributeName;           
```
```
//字体下划线颜色属性 必须是CGColorRef对象，默认为前景色
const CFStringRef kCTUnderlineStyleAttributeName;           
```
```
//字体下划线样式属性 必须是CFNumberRef对象,默为kCTUnderlineStyleNone 可以通过CTUnderlineStypleModifiers 进行修改下划线风格
const CFStringRef kCTVerticalFormsAttributeName;
```
```
//文字的字形方向属性 必须是CFBooleanRef 默认为false，false表示水平方向，true表示竖直方向
const CFStringRef kCTGlyphInfoAttributeName;
```
```
//字体信息属性 必须是CTGlyphInfo对象
const CFStringRef kCTRunDelegateAttributeName
```
```
//CTRun 委托属性 必须是CTRunDelegate对象
```
举例说明：
[cpp] view plain copy print ?
1. NSMutableAttributedString *mabstring = [[NSMutableAttributedString alloc]initWithString:@"This is a test of characterAttribute. 中文字符"];
```
NSMutableAttributedString *mabstring = [[NSMutableAttributedString alloc]initWithString:@"This is a test of characterAttribute. 中文字符"];
```
[cpp] view plain copy print ?

//设置字体属性

  CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"), 40, NULL);

  [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
```
  //设置字体属性
    CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"), 40, NULL);
    [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)]; 
```
[cpp] view plain copy print ?

//设置斜体字

    CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 14, NULL);

    [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
```
//设置斜体字
    CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 14, NULL);
    [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
```
[cpp] view plain copy print ?

//下划线

[mabstring addAttribute:(id)kCTUnderlineStyleAttributeName value:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] range:NSMakeRange(0, 4)];
```
//下划线
    [mabstring addAttribute:(id)kCTUnderlineStyleAttributeName value:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] range:NSMakeRange(0, 4)]; 
```
[cpp] view plain copy print ?

//下划线颜色

[mabstring addAttribute:(id)kCTUnderlineColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 4)];
```
//下划线颜色
    [mabstring addAttribute:(id)kCTUnderlineColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 4)];
```
[cpp] view plain copy print ?
1. //设置字体简隔 eg:test
2. long number = 10;
3. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
4. [mabstring addAttribute:(id)kCTKernAttributeName value:(id)num range:NSMakeRange(10, 4)];
```
//设置字体简隔 eg:test 
    long number = 10;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTKernAttributeName value:(id)num range:NSMakeRange(10, 4)];
```
[cpp] view plain copy print ?
1. //设置连字
2. long number = 1;
3. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
4. [mabstring addAttribute:(id)kCTLigatureAttributeName value:(id)num range:NSMakeRange(0, [str length])];
```
//设置连字
long number = 1;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTLigatureAttributeName value:(id)num range:NSMakeRange(0, [str length])];
```
连字还不会使用，未看到效果。
[cpp] view plain copy print ?
1. //设置字体颜色
2. [mabstring addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 9)];
```
//设置字体颜色
    [mabstring addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 9)];
```
[cpp] view plain copy print ?
1. //设置字体颜色为前影色
2. CFBooleanRef flag = kCFBooleanTrue;
3. [mabstring addAttribute:(id)kCTForegroundColorFromContextAttributeName value:(id)flag range:NSMakeRange(5, 10)];
```
//设置字体颜色为前影色
    CFBooleanRef flag = kCFBooleanTrue;
    [mabstring addAttribute:(id)kCTForegroundColorFromContextAttributeName value:(id)flag range:NSMakeRange(5, 10)];
```
无明显效果。
[cpp] view plain copy print ?
1. //设置空心字
2. long number = 2;
3. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
4. [mabstring addAttribute:(id)kCTStrokeWidthAttributeName value:(id)num range:NSMakeRange(0, [str length])];
```
//设置空心字
    long number = 2;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTStrokeWidthAttributeName value:(id)num range:NSMakeRange(0, [str length])];
```
[cpp] view plain copy print ?
1. //设置空心字
2. long number = 2;
3. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
4. [mabstring addAttribute:(id)kCTStrokeWidthAttributeName value:(id)num range:NSMakeRange(0, [str length])];
6. //设置空心字颜色
7. [mabstring addAttribute:(id)kCTStrokeColorAttributeName value:(id)[UIColor greenColor].CGColor range:NSMakeRange(0, [str length])];
```
//设置空心字
    long number = 2;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTStrokeWidthAttributeName value:(id)num range:NSMakeRange(0, [str length])];
     
    //设置空心字颜色
    [mabstring addAttribute:(id)kCTStrokeColorAttributeName value:(id)[UIColor greenColor].CGColor range:NSMakeRange(0, [str length])];
```
在设置空心字颜色时，必须先将字体高为空心，否则设置颜色是没有效果的。
[cpp] view plain copy print ?
1. //对同一段字体进行多属性设置
2. //红色
3. NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)[UIColor redColor].CGColor forKey:(id)kCTForegroundColorAttributeName];
4. //斜体
5. CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 40, NULL);
6. [attributes setObject:(id)font forKey:(id)kCTFontAttributeName];
7. //下划线
8. [attributes setObject:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] forKey:(id)kCTUnderlineStyleAttributeName];
10. [mabstring addAttributes:attributes range:NSMakeRange(0, 4)];
```
//对同一段字体进行多属性设置    
    //红色
    NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)[UIColor redColor].CGColor forKey:(id)kCTForegroundColorAttributeName];
    //斜体
    CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 40, NULL);
    [attributes setObject:(id)font forKey:(id)kCTFontAttributeName];
    //下划线
    [attributes setObject:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] forKey:(id)kCTUnderlineStyleAttributeName];
    
    [mabstring addAttributes:attributes range:NSMakeRange(0, 4)];
```
最后是draw了。
[cpp] view plain copy print ?
1. -(void)characterAttribute
2. {
3. NSString *str = @"This is a test of characterAttribute. 中文字符";
4. NSMutableAttributedString *mabstring = [[NSMutableAttributedString alloc]initWithString:str];
6. [mabstring beginEditing];
7. /*
8. long number = 1;
9. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
10. [mabstring addAttribute:(id)kCTCharacterShapeAttributeName value:(id)num range:NSMakeRange(0, 4)];
11. */
12. /*
13. //设置字体属性
14. CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"), 40, NULL);
15. [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
16. */
17. /*
18. //设置字体简隔 eg:test
19. long number = 10;
20. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
21. [mabstring addAttribute:(id)kCTKernAttributeName value:(id)num range:NSMakeRange(10, 4)];
22. */
24. /*
25. long number = 1;
26. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
27. [mabstring addAttribute:(id)kCTLigatureAttributeName value:(id)num range:NSMakeRange(0, [str length])];
28. */
29. /*
30. //设置字体颜色
31. [mabstring addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 9)];
32. */
33. /*
34. //设置字体颜色为前影色
35. CFBooleanRef flag = kCFBooleanTrue;
36. [mabstring addAttribute:(id)kCTForegroundColorFromContextAttributeName value:(id)flag range:NSMakeRange(5, 10)];
37. */
39. /*
40. //设置空心字
41. long number = 2;
42. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
43. [mabstring addAttribute:(id)kCTStrokeWidthAttributeName value:(id)num range:NSMakeRange(0, [str length])];
45. //设置空心字颜色
46. [mabstring addAttribute:(id)kCTStrokeColorAttributeName value:(id)[UIColor greenColor].CGColor range:NSMakeRange(0, [str length])];
47. */
49. /*
50. long number = 1;
51. CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
52. [mabstring addAttribute:(id)kCTSuperscriptAttributeName value:(id)num range:NSMakeRange(3, 1)];
53. */
55. /*
56. //设置斜体字
57. CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 14, NULL);
58. [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
59. */
61. /*
62. //下划线
63. [mabstring addAttribute:(id)kCTUnderlineStyleAttributeName value:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] range:NSMakeRange(0, 4)];
64. //下划线颜色
65. [mabstring addAttribute:(id)kCTUnderlineColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 4)];
66. */
70. //对同一段字体进行多属性设置
71. //红色
72. NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)[UIColor redColor].CGColor forKey:(id)kCTForegroundColorAttributeName];
73. //斜体
74. CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 40, NULL);
75. [attributes setObject:(id)font forKey:(id)kCTFontAttributeName];
76. //下划线
77. [attributes setObject:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] forKey:(id)kCTUnderlineStyleAttributeName];
79. [mabstring addAttributes:attributes range:NSMakeRange(0, 4)];
83. NSRange kk = NSMakeRange(0, 4);
85. NSDictionary * dc = [mabstring attributesAtIndex:0 effectiveRange:&kk];
87. [mabstring endEditing];
89. NSLog(@"value = %@",dc);
93. CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)mabstring);
95. CGMutablePathRef Path = CGPathCreateMutable();
97. CGPathAddRect(Path, NULL ,CGRectMake(10 , 0 ,self.bounds.size.width-10 , self.bounds.size.height-10));
99. CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), Path, NULL);
101. //获取当前(View)上下文以便于之后的绘画，这个是一个离屏。
102. CGContextRef context = UIGraphicsGetCurrentContext();
104. CGContextSetTextMatrix(context , CGAffineTransformIdentity);
106. //压栈，压入图形状态栈中.每个图形上下文维护一个图形状态栈，并不是所有的当前绘画环境的图形状态的元素都被保存。图形状态中不考虑当前路径，所以不保存
107. //保存现在得上下文图形状态。不管后续对context上绘制什么都不会影响真正得屏幕。
108. CGContextSaveGState(context);
110. //x，y轴方向移动
111. CGContextTranslateCTM(context , 0 ,self.bounds.size.height);
113. //缩放x，y轴方向缩放，－1.0为反向1.0倍,坐标系转换,沿x轴翻转180度
114. CGContextScaleCTM(context, 1.0 ,-1.0);
116. CTFrameDraw(frame,context);
118. CGPathRelease(Path);
119. CFRelease(framesetter);
120. }
```
-(void)characterAttribute
{
    NSString *str = @"This is a test of characterAttribute. 中文字符";
    NSMutableAttributedString *mabstring = [[NSMutableAttributedString alloc]initWithString:str];
    
    [mabstring beginEditing];
    /*
    long number = 1;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTCharacterShapeAttributeName value:(id)num range:NSMakeRange(0, 4)];
    */
    /*
    //设置字体属性
    CTFontRef font = CTFontCreateWithName(CFSTR("Georgia"), 40, NULL);
    [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
    */
    /*
    //设置字体简隔 eg:test 
    long number = 10;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTKernAttributeName value:(id)num range:NSMakeRange(10, 4)];
    */

    /*
    long number = 1;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTLigatureAttributeName value:(id)num range:NSMakeRange(0, [str length])];
     */
    /*
    //设置字体颜色
    [mabstring addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 9)];
     */
    /*
    //设置字体颜色为前影色
    CFBooleanRef flag = kCFBooleanTrue;
    [mabstring addAttribute:(id)kCTForegroundColorFromContextAttributeName value:(id)flag range:NSMakeRange(5, 10)];
     */
    
    /*
    //设置空心字
    long number = 2;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTStrokeWidthAttributeName value:(id)num range:NSMakeRange(0, [str length])];
     
    //设置空心字颜色
    [mabstring addAttribute:(id)kCTStrokeColorAttributeName value:(id)[UIColor greenColor].CGColor range:NSMakeRange(0, [str length])];
     */
    
    /*
    long number = 1;
    CFNumberRef num = CFNumberCreate(kCFAllocatorDefault,kCFNumberSInt8Type,&number);
    [mabstring addAttribute:(id)kCTSuperscriptAttributeName value:(id)num range:NSMakeRange(3, 1)];
    */
    
    /*
    //设置斜体字
    CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 14, NULL);
    [mabstring addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, 4)];
    */ 
    
    /*
    //下划线
    [mabstring addAttribute:(id)kCTUnderlineStyleAttributeName value:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] range:NSMakeRange(0, 4)]; 
    //下划线颜色
    [mabstring addAttribute:(id)kCTUnderlineColorAttributeName value:(id)[UIColor redColor].CGColor range:NSMakeRange(0, 4)];
     */
    
    
    
    //对同一段字体进行多属性设置    
    //红色
    NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)[UIColor redColor].CGColor forKey:(id)kCTForegroundColorAttributeName];
    //斜体
    CTFontRef font = CTFontCreateWithName((CFStringRef)[UIFont italicSystemFontOfSize:20].fontName, 40, NULL);
    [attributes setObject:(id)font forKey:(id)kCTFontAttributeName];
    //下划线
    [attributes setObject:(id)[NSNumber numberWithInt:kCTUnderlineStyleDouble] forKey:(id)kCTUnderlineStyleAttributeName];
    
    [mabstring addAttributes:attributes range:NSMakeRange(0, 4)];
     

    
    NSRange kk = NSMakeRange(0, 4);
    
    NSDictionary * dc = [mabstring attributesAtIndex:0 effectiveRange:&kk];
    
    [mabstring endEditing];
    
    NSLog(@"value = %@",dc);
    

    
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)mabstring);
    
    CGMutablePathRef Path = CGPathCreateMutable();
    
    CGPathAddRect(Path, NULL ,CGRectMake(10 , 0 ,self.bounds.size.width-10 , self.bounds.size.height-10));
    
    CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), Path, NULL);	
    
    //获取当前(View)上下文以便于之后的绘画，这个是一个离屏。
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGContextSetTextMatrix(context , CGAffineTransformIdentity);
    
    //压栈，压入图形状态栈中.每个图形上下文维护一个图形状态栈，并不是所有的当前绘画环境的图形状态的元素都被保存。图形状态中不考虑当前路径，所以不保存
    //保存现在得上下文图形状态。不管后续对context上绘制什么都不会影响真正得屏幕。
    CGContextSaveGState(context);
    
    //x，y轴方向移动
    CGContextTranslateCTM(context , 0 ,self.bounds.size.height);
    
    //缩放x，y轴方向缩放，－1.0为反向1.0倍,坐标系转换,沿x轴翻转180度
    CGContextScaleCTM(context, 1.0 ,-1.0);
    
    CTFrameDraw(frame,context);
    
    CGPathRelease(Path);
    CFRelease(framesetter);
}
```
[cpp] view plain copy print ?
1. - (void)drawRect:(CGRect)rect
2. {
3. [self characterAttribute];
4. }
```
- (void)drawRect:(CGRect)rect
{
    [self characterAttribute];
}
```
CORETEXT框架图

另对于Context的了解可以参考:http://www.padovo.com/blog/2013/01/31/study-coretext/
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原文地址：https://www.cnblogs.com/yulang314/p/3567128.html