NSParagraphStyle 的属性

UILabel * label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
    label.font = [UIFont systemFontOfSize:14];
    label.numberOfLines = 0;
    [self.view addSubview:label];
    [label mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.offset(20);
        make.right.offset(-20);
        make.top.offset(160);
    }];
    NSString * desc = @"这是一段titlte文案，这是一段titlte文案,这是一段titlte文案,这是一段titlte文案后面是一个换行\nThis morning (March 29th), most cities and counties in Guangdong were cloudy and covered with light fog. Some areas in Qingyuan, Shaoguan and Zhaoqing saw dense fog with visibility of less than 500 meters.\n\n这是一段titlte文案，后面是一个换行\n";
    NSMutableParagraphStyle * style = [NSMutableParagraphStyle defaultParagraphStyle].mutableCopy;
    style.paragraphSpacing = 10; //当前段落和下一个段落的距离
    style.paragraphSpacingBefore = 5;//当前段落和上一个段落的距离
    style.lineSpacing = 20;//当前行和下一行的距离，空白行也存在间距，这个间距在行下
//    style.lineHeightMultiple = 2.0; //这个间距在行上
    style.firstLineHeadIndent = 30; //当前段落第一行的偏移量
    style.headIndent = 20;  //当前段落其他行的偏移量
    style.lineBreakMode = NSLineBreakByWordWrapping;//截断模式
//    style.tailIndent = -16; //为正数时代表显示宽度，为负数时代表距离右边的间距
//    style.alignment = NSTextAlignmentRight; //对齐方式
    //书写方向
//    style.baseWritingDirection = NSWritingDirectionRightToLeft;
    style.hyphenationFactor = 1.0; //0 or 1
    NSDictionary * dict = @{
                            NSFontAttributeName:[UIFont systemFontOfSize:18],
                            NSForegroundColorAttributeName:[UIColor blackColor],
                            NSParagraphStyleAttributeName:style,
                            NSBackgroundColorAttributeName:[UIColor redColor]
                            };
    NSAttributedString * attr = [[NSAttributedString alloc] initWithString:desc attributes:dict];
    label.attributedText = attr;