NSCalendar dateFromComponents 返回错误的日期

Question

我正在 NSDate 上编写一个类别，以从 ISO 8601 字符串表示 (YYYYMMDD) 创建一个 NSDate。

即使我通过了 20010226，我还是会回到 2001-02-25 23:00:00 +0000。我做错了什么？

这是代码：

-(id) initWithISO8601Date: (NSString *) iso8601Date{
    // Takes a date in the YYYYMMDD form


    int year = [[iso8601Date substringWithRange:NSMakeRange(0, 4)] integerValue];
    int month = [[iso8601Date substringWithRange:NSMakeRange(4, 2)] integerValue];
    int day = [[iso8601Date substringWithRange:NSMakeRange(6,2)] integerValue];

    NSDateComponents *comps = [[NSDateComponents alloc] init];
    [comps setYear:year];
    [comps setMonth:month];
    [comps setDay:day];


    self = [[NSCalendar currentCalendar] dateFromComponents:comps];
    NSLog(@"%@", self);

    [comps release];

    return self;

}

Answer 1

问题出在时区（我在 GMT -1）。正确的代码是：

-(id) initWithISO8601Date: (NSString *) iso8601Date{
    // Takes a date in the YYYYMMDD form
    int year = [[iso8601Date substringWithRange:NSMakeRange(0, 4)] integerValue];
    int month = [[iso8601Date substringWithRange:NSMakeRange(4, 2)] integerValue];
    int day = [[iso8601Date substringWithRange:NSMakeRange(6,2)] integerValue];

    NSDateComponents *comps = [[NSDateComponents alloc] init];
    [comps setYear:year];
    [comps setMonth:month];
    [comps setDay:day];

    NSCalendar *cal = [NSCalendar currentCalendar];
    [cal setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"GMT"]];
    self = [cal dateFromComponents:comps];


    [comps release];

    return self;

}