iphone - 如何从 NSDate 中减去小时数？

Question

我想从约会中减去 4 小时。我使用以下代码将日期字符串读入 NSDate 对象:

NSDateFormatter * dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZ"];
NSDate * mydate = [dateFormatter dateFromString:[dict objectForKey:@"published"]];

接下来我该做什么？

Answer 1

NSDate *newDate = [theDate dateByAddingTimeInterval:-3600*4];

Link to documentation .

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NSDate *newDate = [[[NSDate alloc] initWithTimeInterval:-3600*4
                                              sinceDate:theDate]] autorelease];

Link to documentation .