iOS 文本首行缩进

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];
    paragraphStyle.lineHeightMultiple = 20.f;
    paragraphStyle.maximumLineHeight = 25.f;
    paragraphStyle.minimumLineHeight = 15.f;
    paragraphStyle.firstLineHeadIndent = 20.f; // 首行缩进
    paragraphStyle.alignment = NSTextAlignmentJustified;
    NSMutableDictionary *attributes = [@{ NSFontAttributeName:[UIFont systemFontOfSize:15], NSParagraphStyleAttributeName:paragraphStyle, NSForegroundColorAttributeName:[UIColor colorWithRed:153/255. green:102/255. blue:51/255. alpha:1]
                                          }mutableCopy];
    self.textView.attributedText = [[NSAttributedString alloc]initWithString:@"ssssssssssssssssssssssss" attributes:attributes];
}