你不需要尽可能多的单引号(只需要非日期/时间字符)，所以改变这个:

You don't need near as many single quotes as you have (only needed on non date/time characters), so change this:

[self.dateFormatter setDateFormat:@"yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'"];

为此:

[self.dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZZZ"];
...
self.currentQuestion.updated = [self.dateFormatter dateFromString:[self.currentParsedCharacterData stringByReplacingOccurrencesOfString:@":" withString:@"" options:0 range:NSMakeRange([self.currentParsedCharacterData length] – 5,5)]];

此处的文档:https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html#//apple_ref/doc/uid/TP40002369-SW1

Unicode 格式模式:http://unicode.org/reports/tr35/tr35-6.html#Date_Format_Patterns

Unicode Format Patterns: http://unicode.org/reports/tr35/tr35-6.html#Date_Format_Patterns

处理带冒号的时区 (+00:00):http://petersteinberger.com/2010/05/nsdateformatter-and-0000-parsing/

Dealing with TimeZones with Colons (+00:00): http://petersteinberger.com/2010/05/nsdateformatter-and-0000-parsing/