typedef NS_ENUM(NSInteger, NSLineBreakMode) {
   NSLineBreakByWordWrapping = 0, 
   NSLineBreakByCharWrapping,
   NSLineBreakByClipping, //减掉后面显示不了的部分
   NSLineBreakByTruncatingHead,  //头部内容以......方式省略
   NSLineBreakByTruncatingTail,    //尾部内容以......方式省略
   NSLineBreakByTruncatingMiddle  //中间内容以......方式省略
} NS_ENUM_AVAILABLE_IOS(6_0);```

typedef NS_ENUM(NSInteger, NSStringDrawingOptions) {
NSStringDrawingTruncatesLastVisibleLine = 1 << 5, // Truncates and adds the ellipsis character to the last visible line if the text doesn't fit into the bounds specified. Ignored if NSStringDrawingUsesLineFragmentOrigin is not also set.
NSStringDrawingUsesLineFragmentOrigin = 1 << 0, // The specified origin is the line fragment origin, not the base line origin
NSStringDrawingUsesFontLeading = 1 << 1, // Uses the font leading for calculating line heights
NSStringDrawingUsesDeviceMetrics = 1 << 3, // Uses image glyph bounds instead of typographic bounds
} NS_ENUM_AVAILABLE_IOS(6_0);

typedef NS_ENUM(NSInteger, NSWritingDirection) {
NSWritingDirectionNatural = -1, // Determines direction using the Unicode Bidi Algorithm rules P2 and P3
NSWritingDirectionLeftToRight = 0, // Left to right writing direction 左到右的书写方向
NSWritingDirectionRightToLeft = 1 // Right to left writing direction 右到左的书写方向
} NS_ENUM_AVAILABLE_IOS(6_0);```

#段落风格
// NSParagraphStyleAttributeName 段落的风格（设置首行，行间距，对齐方式什么的）看自己需要什么属性，写什么 
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init]; 
paragraphStyle.lineSpacing = 10;// 字体的行间距 
paragraphStyle.firstLineHeadIndent = 20.0f;//首行缩进 
paragraphStyle.alignment = NSTextAlignmentJustified;//（两端对齐的）文本对齐方式：（左，中，右，两端对齐，自然）
paragraphStyle.lineBreakMode = NSLineBreakByTruncatingTail;//结尾部分的内容以……方式省略 ( "...wxyz" ,"abcd..." ,"ab...yz") 
paragraphStyle.headIndent = 20;//整体缩进(首行除外) 
paragraphStyle.tailIndent = 20;// 
paragraphStyle.minimumLineHeight = 10;//最低行高 
paragraphStyle.maximumLineHeight = 20;//最大行高 
paragraphStyle.paragraphSpacing = 15;//段与段之间的间距 
paragraphStyle.paragraphSpacingBefore = 22.0f;//段首行空白空间/* Distance between the bottom of the previous paragraph (or the end of its paragraphSpacing, if any) and the top of this paragraph. */ 
paragraphStyle.baseWritingDirection = NSWritingDirectionLeftToRight;//从左到右的书写方向（一共➡️三种）
paragraphStyle.lineHeightMultiple = 15;/* Natural line height is multiplied by this factor (if positive) before being constrained by minimum and maximum line height. */ 
paragraphStyle.hyphenationFactor = 1;//连字属性 在iOS，唯一支持的值分别为0和1

#字体大小
/*  NSFontAttributeName 字体大小  NSParagraphStyleAttributeName 段落的风格（设置首行，行间距，对齐方式什么的）  NSKernAttributeName 字间距  */
 NSDictionary *attributes = @{        
       NSFontAttributeName:[UIFont systemFontOfSize:15],             
       NSParagraphStyleAttributeName:paragraphStyle,         
       NSKernAttributeName:@(10),                       
  }; 

#应用
textView.attributedText = [[NSAttributedString alloc] initWithString:textView.text attributes:attributes];