Foundation-几种段落排版格式NSMutableParagraphStyle

一、框架中的原始定义如下：

@property(readwrite)CGFloat lineSpacing;        //行间距
@property(readwrite)CGFloat paragraphSpacing;    //段落间距
@property(readwrite)NSTextAlignment alignment;   //文字对齐格式
@property(readwrite)CGFloat firstLineHeadIndent; //首行缩进
@property(readwrite)CGFloat headIndent;         //行首缩进
@property(readwrite)CGFloat tailIndent;         //行尾缩进
@property(readwrite)NSLineBreakMode lineBreakMode;//段落文字溢出隐藏方式
@property(readwrite)CGFloat minimumLineHeight;   //最小行高
@property(readwrite)CGFloat maximumLineHeight;    //最大行高
@property(readwrite)NSWritingDirection baseWritingDirection;//段落书写方向
@property(readwrite)CGFloat lineHeightMultiple;   //多行行高
@property(readwrite)CGFloat paragraphSpacingBefore;//段落前间距
@property(readwrite)float hyphenationFactor;     //英文断字连字符

二、NSTextAlignment文字对齐方式枚举(IOS6以上有效)：

NSTextAlignmentLeft     //居左

NSTextAlignmentRight    //居右

NSTextAlignmentCenter   //居中

NSTextAlignmentNatural   //默认

NSTextAlignmentJustified //自调整

三、NSWritingDirection文字书写方向(IOS6以上有效)：

NSWritingDirectionNatural     //使用Bidi算法规则P2和P3定义方向

NSWritingDirectionLeftToRight //从左向右

NSWritingDirectionRightToLeft  //从右向左

示例源码：

NSString*text=@"秋叶黄,秋叶黄,我深深的沉醉其中,摇摆的叶片,枯黄着也是秋天,飘落着也是秋天;秋叶黄,秋叶黄,你随风悄悄的散去,枯萎的树枝,下着雨也是秋天,吹着风也是秋天.";

  //就用这两个options枚举参数吧，我也不知道为啥
   NSStringDrawingOptions options =NSStringDrawingUsesLineFragmentOrigin |NSStringDrawingUsesFontLeading;
   // labelW是段落的固定宽度；CGFLOAT_MAX固定用这个；attributes按照下面的语句fontSize是字体的大小
   // >IOS7
   CGFloat labelH = [textboundingRectWithSize:CGSizeMake(labelW, CGFLOAT_MAX)options:options attributes:@{NSFontAttributeName:[UIFontsystemFontOfSize:fontSize]} context:nil].size.height;
   //
   //CGFloat labelH = [text sizeWithFont:[UIFontsystemFontOfSize:fontSize] constrainedToSize:CGSizeMake(labelW,CGFLOAT_MAX)].height;
  //打印计算的高度看一下
   NSLog(@"文字段落高度为：%f",labelH);
   //实际行数
   NSInteger lineNum = labelH/fontSize;

   NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc ] init];
   //文字对齐方式
   paragraphStyle.alignment =NSTextAlignmentJustified;
  //段落首字符缩进两个字
   paragraphStyle.firstLineHeadIndent =2*fontSize;
   //行间距
   paragraphStyle.lineSpacing =lingSpace;
  //属性字典,包括前景字体颜色和段落属性
   NSDictionary *attributes =@{NSForegroundColorAttributeName:[UIColorredColor],NSParagraphStyleAttributeName:paragraphStyle};
   //属性字符串
   NSAttributedString *attributedText = [[NSAttributedString alloc ] initWithString : text attributes:attributes];

   UILabel *label1 = [[UILabel alloc]initWithFrame:CGRectMake(0, 70, 300,labelH+lineNum*lingSpace)];
   //文字行数设置为0
   label1.numberOfLines = 0;
   // label背景色
   label1.backgroundColor = [UIColorgreenColor];
   label1.attributedText =attributedText;
   //显示label

   [self.view addSubview:label1];