设置UITextView，UILabel中的字体格式（行间距，段落）

NSMutableAttributedString * str = [[NSMutableAttributedString alloc]initWithString:kRule];

NSMutableParagraphStyle * paragraph = [[NSMutableParagraphStyle alloc]init];

[paragraph setLineSpacing:6];//设置行间距

[paragraph setParagraphSpacing:6];//设置段落间距

[paragraph setAlignment:NSTextAlignmentLeft];//设置对齐方式

[paragraph setFirstLineHeadIndent:2];//设置首行缩进

[paragraph setHeadIndent:2];//设置头缩进

[paragraph setTailIndent:2];//设置尾缩进

[paragraph setLineBreakMode:NSLineBreakByCharWrapping];//设置换行方式

[paragraph setMinimumLineHeight:2];//设置最小行高

[paragraph setMaximumLineHeight:10];//设置最大行高

[paragraph setBaseWritingDirection:NSWritingDirectionNatural];//设置书写方向

[paragraph setLineHeightMultiple:4];//设置可变行高

[paragraph setParagraphSpacingBefore:10];//设置段后间距

[str addAttribute:NSParagraphStyleAttributeName value:paragraph range:NSMakeRange(0, str.length)];

label.attributedText = str;