最后得到解决方案：

strong> NSDate对象没有与他们相关的时区，并且有一些发布回苹果的人决定NSDate的描述方法，这是NSLog使用的，应该使用GMT + 0而不是本地时间输出区。 （我假设有人有一个错误，他们损坏了他们的区域设置，并导致NSDate的描述方法崩溃，所以错误报告已经提交...）

The point is, NSDate objects don't have a time zone associated with them, and a few releases back someone in Apple decided that NSDate's -description method, which is what NSLog uses, should use GMT+0 and NOT the local time zone for output. (I assume someone had a bug where they corrupted their locale setting, and that caused NSDate's -description method to crash, and so bug reports got filed...)

简短版本：使用NSDateFormatter输出日期。不要使用-description 。