code> NSTimeZone 是一个输出参数，因此您需要传递一个指针，如下所示：

The NSTimeZone is an output parameter, so you need to pass a pointer to a pointer, like this:

NSTimeZone *theTimeZone = nil;
group.updatedAt = [formatter dateFromString:someString timeZone:&theTimeZone];

当函数返回时， theTimeZone 设置为函数的输出值。

When the function returns, theTimeZone will be set to the output value of the function.