此异常是NSXMLParser类的一个错误，它指示XML解析器在处理实体引用时缺少了分号。一些XML文件中在实体引用后少了分号可能会导致出现此错误。解决这个错误的方法是确保所有实体引用之后都包含一个分号。
以下是两个示例说明：
示例1
NSString *xmlString = @"<?xml version='1.0' encoding='UTF-8'?><book><title>The Lion, the Witch and the Wardrobe</title><author>C. S. Lewis</author><published_year>1950<published_year><genre>fantasy<genre></book>";
NSData *xmlData = [xmlString dataUsingEncoding:NSUTF8StringEncoding];
NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithData:xmlData];
xmlParser.delegate = self;
[xmlParser parse];
如果在XML文档中缺少分号，会抛出”NSXMLParserEntityRefMissingSemiError”异常。例如以下XML字符串在published_year元素中缺少了分号。
NSString *xmlString = @"<?xml version='1.0' encoding='UTF-8'?><book><title>The Lion, the Witch and the Wardrobe</title><author>C. S. Lewis</author><published_year>1950</published_year><genre>fantasy</genre></book>";
应该这样更正：
NSString *xmlString = @"<?xml version='1.0' encoding='UTF-8'?><book><title>The Lion, the Witch and the Wardrobe</title><author>C. S. Lewis</author><published_year>1950</published_year><genre>fantasy</genre></book>";
示例2
在XML文档中，字符实体引用由”＆”和实体名称或实体号码组成，实体号码则由’#’和十进制数字组成。实体引用必须以’;’结尾，否则会导致出现”NSXMLParserEntityRefMissingSemiError”异常。
例如，在以下XML字符串中，＆lt字符实体引用没有以’;’结尾：
NSString *xmlString = @"<?xml version='1.0' encoding='UTF-8'?><book><title>The Lion, the Witch and the Wardrobe</title><author>C. S. Lewis</author><description>In <em>The Chronicles of Narnia</em> series, a group of children travels to a magical land through a wardrobe.</description></book>";
应该这样更正：
NSString *xmlString = @"<?xml version='1.0' encoding='UTF-8'?><book><title>The Lion, the Witch and the Wardrobe</title><author>C. S. Lewis</author><description>In <em>The Chronicles of Narnia</em> series, a group of children travels to a magical land through a wardrobe.</description></book>";