IOS CoreText.framework --- 段落样子CTParagraphStyle
在前面一篇文章中，介绍了属性文字的基本使用，本章节主要针对文字的段落样式展开演示说明。
先定义一段演示文字（文字中有中，英文）。
NSString *src = [NSString stringWithString:@"其实流程是这样的： 1、生成要绘制的NSAttributedString对象。 2、生成一个CTFramesetterRef对象，然后创建一个CGPath对象，这个Path对象用于表示可绘制区域坐标值、长宽。 3、使用上面生成的setter和path生成一个CTFrameRef对象，这个对象包含了这两个对象的信息（字体信息、坐标信息），它就可以使用CTFrameDraw方法绘制了。"];
NSMutableAttributedString * mabstring = [[NSMutableAttributedString alloc]initWithString:src];
long slen = [mabstring length]; 在未设置段落样式的情况下，效果：从上面的交果来看，想必大家也看到了，英文部份换行显示了。这个一般情况下不注意，但在大的段落文章中就会出现不对齐现象。
先不管上面的，下面逐个来演示一下段落属性。
段落样式定义：
kCTParagraphStyleSpecifierAlignment = 0, //对齐属性
kCTParagraphStyleSpecifierFirstLineHeadIndent = 1, //首行缩进
kCTParagraphStyleSpecifierHeadIndent = 2, //段头缩进
kCTParagraphStyleSpecifierTailIndent = 3, //段尾缩进
kCTParagraphStyleSpecifierTabStops = 4, //制表符模式
kCTParagraphStyleSpecifierDefaultTabInterval = 5, //默认tab间隔
kCTParagraphStyleSpecifierLineBreakMode = 6, //换行模式
kCTParagraphStyleSpecifierLineHeightMultiple = 7, //多行高
kCTParagraphStyleSpecifierMaximumLineHeight = 8, //最大行高
kCTParagraphStyleSpecifierMinimumLineHeight = 9, //最小行高
kCTParagraphStyleSpecifierLineSpacing = 10, //行距
kCTParagraphStyleSpecifierParagraphSpacing = 11, //段落间距 在段的未尾（Bottom）加上间隔，这个值为负数。
kCTParagraphStyleSpecifierParagraphSpacingBefore = 12, //段落前间距 在一个段落的前面加上间隔。TOP
kCTParagraphStyleSpecifierBaseWritingDirection = 13, //基本书写方向
kCTParagraphStyleSpecifierMaximumLineSpacing = 14, //最大行距
kCTParagraphStyleSpecifierMinimumLineSpacing = 15, //最小行距
kCTParagraphStyleSpecifierLineSpacingAdjustment = 16, //行距调整
kCTParagraphStyleSpecifierCount = 17, //
对齐属性：
kCTLeftTextAlignment = 0, //左对齐 kCTRightTextAlignment = 1, //右对齐 kCTCenterTextAlignment = 2, //居中对齐 kCTJustifiedTextAlignment = 3, //文本对齐 kCTNaturalTextAlignment = 4 //自然文本对齐段落默认样式为
kCTNaturalTextAlignment
效果：
居中：
文本对齐Justified效果
对齐方式设置代码：
CTTextAlignment alignment = kCTJustifiedTextAlignment;
CTParagraphStyleSetting alignmentStyle;
alignmentStyle.spec=kCTParagraphStyleSpecifierAlignment;//指定为对齐属性
alignmentStyle.valueSize=sizeof(alignment);
alignmentStyle.value=&alignment;首行缩进代码：
//首行缩进
CGFloat fristlineindent = 24.0f;
CTParagraphStyleSetting fristline;
fristline.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;
fristline.value = &fristlineindent;
fristline.valueSize = sizeof(float);效果：
段头缩进代码：
//段缩进
CGFloat headindent = 10.0f;
CTParagraphStyleSetting head;
head.spec = kCTParagraphStyleSpecifierHeadIndent;
head.value = &headindent;
head.valueSize = sizeof(float);段尾缩进代码：
//段尾缩进
CGFloat tailindent = 50.0f;
CTParagraphStyleSetting tail;
tail.spec = kCTParagraphStyleSpecifierTailIndent;
tail.value = &tailindent;
tail.valueSize = sizeof(float);
效果：
制表符（tab）代码：
//tab
CTTextAlignment tabalignment = kCTJustifiedTextAlignment;
CTTextTabRef texttab = CTTextTabCreate(tabalignment, 24, NULL);
CTParagraphStyleSetting tab;
tab.spec = kCTParagraphStyleSpecifierTabStops;
tab.value = &texttab;
tab.valueSize = sizeof(CTTextTabRef);效果（未看出哪有变化感觉行距大了点）：
换行模式：
kCTLineBreakByWordWrapping = 0, //出现在单词边界时起作用，如果该单词不在能在一行里显示时，整体换行。此为段的默认值。 kCTLineBreakByCharWrapping = 1, //当一行中最后一个位置的大小不能容纳一个字符时，才进行换行。 kCTLineBreakByClipping = 2, //超出画布边缘部份将被截除。 kCTLineBreakByTruncatingHead = 3, //截除前面部份，只保留后面一行的数据。前部份以...代替。 kCTLineBreakByTruncatingTail = 4, //截除后面部份，只保留前面一行的数据，后部份以...代替。 kCTLineBreakByTruncatingMiddle = 5 //在一行中显示段文字的前面和后面文字，中间文字使用...代替。换行模式代码：
//换行模式
CTParagraphStyleSetting lineBreakMode;
CTLineBreakMode lineBreak = kCTLineBreakByWordWrapping;//kCTLineBreakByCharWrapping;//换行模式
lineBreakMode.spec = kCTParagraphStyleSpecifierLineBreakMode;
lineBreakMode.value = &lineBreak;
lineBreakMode.valueSize = sizeof(CTLineBreakMode);kCTLineBreakByWordWrapping效果：
kCTLineBreakByCharWrapping效果:
kCTLineBreakByClipping效果：
kCTLineBreakByTruncatingHead效果：
kCTLineBreakByTruncatingTail效果：
kCTLineBreakByTruncatingMiddle效果：
多行高设置代码：
//多行高
CGFloat MutiHeight = 10.0f;
CTParagraphStyleSetting Muti;
Muti.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
Muti.value = &MutiHeight;
Muti.valueSize = sizeof(float);最大行高代码：
//最大行高
CGFloat MaxHeight = 5.0f;
CTParagraphStyleSetting Max;
Max.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
Max.value = &MaxHeight;
Max.valueSize = sizeof(float);效果：
行距代码：
//行距
CGFloat _linespace = 5.0f;
CTParagraphStyleSetting lineSpaceSetting;
lineSpaceSetting.spec = kCTParagraphStyleSpecifierLineSpacing;
lineSpaceSetting.value = &_linespace;
lineSpaceSetting.valueSize = sizeof(float);效果：
段前间距设置代码（段与段之间）：
//段前间隔
CGFloat paragraphspace = 5.0f;
CTParagraphStyleSetting paragraph;
paragraph.spec = kCTParagraphStyleSpecifierLineSpacing;
paragraph.value = ¶graphspace;
paragraph.valueSize = sizeof(float);kCTWritingDirectionNatural = -1, //普通书写方向，一般习惯是从左到右写 kCTWritingDirectionLeftToRight = 0, //从左到右写 kCTWritingDirectionRightToLeft = 1 //从右到左写
基本书写方向代码：
//书写方向
CTWritingDirection wd = kCTWritingDirectionRightToLeft;
CTParagraphStyleSetting writedic;
writedic.spec = kCTParagraphStyleSpecifierBaseWritingDirection;
writedic.value = &wd;
writedic.valueSize = sizeof(CTWritingDirection);效果：
这个跟字体右对齐效果上类似。
好了，段落的API样式介绍到这里，里面还有很多配合设置时的效果。读者自行演示了。
下面附上draw 代码：
-(void)ParagraphStyle
{
NSString *src = [NSString stringWithString:@"其实流程是这样的： 1、生成要绘制的NSAttributedString对象。 2、生成一个CTFramesetterRef对象，然后创建一个CGPath对象，这个Path对象用于表示可绘制区域坐标值、长宽。 3、使用上面生成的setter和path生成一个CTFrameRef对象，这个对象包含了这两个对象的信息（字体信息、坐标信息），它就可以使用CTFrameDraw方法绘制了。"];
//修改windows回车换行为mac的回车换行
//src = [src stringByReplacingOccurrencesOfString:@"\r\n" withString:@"\n"];
NSMutableAttributedString * mabstring = [[NSMutableAttributedString alloc]initWithString:src];
long slen = [mabstring length];
//创建文本对齐方式
CTTextAlignment alignment = kCTRightTextAlignment;//kCTNaturalTextAlignment;
CTParagraphStyleSetting alignmentStyle;
alignmentStyle.spec=kCTParagraphStyleSpecifierAlignment;//指定为对齐属性
alignmentStyle.valueSize=sizeof(alignment);
alignmentStyle.value=&alignment;
//首行缩进
CGFloat fristlineindent = 24.0f;
CTParagraphStyleSetting fristline;
fristline.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;
fristline.value = &fristlineindent;
fristline.valueSize = sizeof(float);
//段缩进
CGFloat headindent = 10.0f;
CTParagraphStyleSetting head;
head.spec = kCTParagraphStyleSpecifierHeadIndent;
head.value = &headindent;
head.valueSize = sizeof(float);
//段尾缩进
CGFloat tailindent = 50.0f;
CTParagraphStyleSetting tail;
tail.spec = kCTParagraphStyleSpecifierTailIndent;
tail.value = &tailindent;
tail.valueSize = sizeof(float);
//tab
CTTextAlignment tabalignment = kCTJustifiedTextAlignment;
CTTextTabRef texttab = CTTextTabCreate(tabalignment, 24, NULL);
CTParagraphStyleSetting tab;
tab.spec = kCTParagraphStyleSpecifierTabStops;
tab.value = &texttab;
tab.valueSize = sizeof(CTTextTabRef);
//换行模式
CTParagraphStyleSetting lineBreakMode;
CTLineBreakMode lineBreak = kCTLineBreakByTruncatingMiddle;//kCTLineBreakByWordWrapping;//换行模式
lineBreakMode.spec = kCTParagraphStyleSpecifierLineBreakMode;
lineBreakMode.value = &lineBreak;
lineBreakMode.valueSize = sizeof(CTLineBreakMode);
//多行高
CGFloat MutiHeight = 10.0f;
CTParagraphStyleSetting Muti;
Muti.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
Muti.value = &MutiHeight;
Muti.valueSize = sizeof(float);
//最大行高
CGFloat MaxHeight = 5.0f;
CTParagraphStyleSetting Max;
Max.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
Max.value = &MaxHeight;
Max.valueSize = sizeof(float);
//行距
CGFloat _linespace = 5.0f;
CTParagraphStyleSetting lineSpaceSetting;
lineSpaceSetting.spec = kCTParagraphStyleSpecifierLineSpacing;
lineSpaceSetting.value = &_linespace;
lineSpaceSetting.valueSize = sizeof(float);
//段前间隔
CGFloat paragraphspace = 5.0f;
CTParagraphStyleSetting paragraph;
paragraph.spec = kCTParagraphStyleSpecifierLineSpacing;
paragraph.value = ¶graphspace;
paragraph.valueSize = sizeof(float);
//书写方向
CTWritingDirection wd = kCTWritingDirectionRightToLeft;
CTParagraphStyleSetting writedic;
writedic.spec = kCTParagraphStyleSpecifierBaseWritingDirection;
writedic.value = &wd;
writedic.valueSize = sizeof(CTWritingDirection);
//组合设置
CTParagraphStyleSetting settings[] = {
alignmentStyle
fristline,
head,
tail,
tab,
lineBreakMode,
Muti,
Max,
lineSpaceSetting,
writedic
indentSetting
};
//通过设置项产生段落样式对象
CTParagraphStyleRef style = CTParagraphStyleCreate(settings, 11);
// build attributes
NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)style forKey:(id)kCTParagraphStyleAttributeName ];
// set attributes to attributed string
[mabstring addAttributes:attributes range:NSMakeRange(0, slen)];
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)mabstring);
CGMutablePathRef Path = CGPathCreateMutable();
//坐标点在左下角
CGPathAddRect(Path, NULL ,CGRectMake(10 , 10 ,self.bounds.size.width-20 , self.bounds.size.height-20));
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);
}
-（void）drawRect:(CGRect)rect
{
[self ParagraphStyle];
}