NSDate与NSDateFormatter 以及设置时区

//将时间字符串转化为NSDate
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat: @"yyyy-MM-dd HH:mm"];
//dateFormatter通过setTimeZone来设置正确的时区

[dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:8]];

NSDate *date=[dateFormatter dateFromString:dateString];
//将NSDate转化为字符串
NSString *dateString=[dateFormatter stringFromDate:date];