IOS：NSDateComponent 的问题

Question

我有这个代码：

- (void) setDataLabel{

for (int k = 0; k<31; k++){

    [[lineSunday objectAtIndex:k] setAlpha:0.00];
    [[arrayDay objectAtIndex:k] setTextColor:[UIColor whiteColor]];
}

NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
[components setYear:2011];
[components setDay:1];
[components setMonth:10];
//NSLog(@"mese:%d", month);
NSCalendar *gregorianCalendar = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDate *firstDate = [gregorianCalendar dateFromComponents:components];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd"];

for (int i = 0; i < 31; i++) {
    NSTimeInterval seconds = 24*60*60 * i;
    NSDate *date = [NSDate dateWithTimeInterval:seconds sinceDate:firstDate];
    NSDateComponents *weekdayComponents = [gregorianCalendar components:NSWeekdayCalendarUnit fromDate:date];
    int weekday = [weekdayComponents weekday];
    NSString *strDate = [dateFormatter stringFromDate: date];
    [[arrayDay objectAtIndex:i] setText:strDate];
    if (weekday == 1) {
        [[arrayDay objectAtIndex:i] setTextColor:[UIColor redColor]];
        [[lineSunday objectAtIndex:i] setAlpha:1.00];
    }
}

这个代码设置了 31 个带有月份日期的标签，一切都很好，但我不明白为什么十月份有连续两个工作日；举个例子：在今年，这段代码在月末一天这样写：

....25 26 27 28 29 30 30

和 30 和 30 是红色，但不应该是这样，应该是这样是

....25 26 27 28 29 30 31

并且只有 30 必须是红色

为什么会发生这种情况？

Answer 1

这是因为夏令时。我们在该循环中每天添加 86400 秒，但一天将有 ​​25 个小时。

编辑：

最好的方法可能是只在循环中获取日期对象，而根本不进行花哨的计算。

- (void) setDataLabel{

    for (int k = 0; k<31; k++){
        [[lineSunday objectAtIndex:k] setAlpha:0.00];
        [[arrayDay objectAtIndex:k] setTextColor:[UIColor whiteColor]];
    }

    NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
    [components setYear:2011];
    [components setMonth:10];
    NSCalendar *gregorianCalendar = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"dd"];

    for (int i = 0; i < 31; i++) {
        [components setDay:i+1];
        NSDate *date = [gregorianCalendar dateFromComponents:components];
        NSDateComponents *weekdayComponents = [gregorianCalendar components:NSWeekdayCalendarUnit fromDate:date];
        int weekday = [weekdayComponents weekday];
        NSString *strDate = [dateFormatter stringFromDate: date];
        [[arrayDay objectAtIndex:i] setText:strDate];
        if (weekday == 1) {
            [[arrayDay objectAtIndex:i] setTextColor:[UIColor redColor]];
            [[lineSunday objectAtIndex:i] setAlpha:1.00];
        }
    }
    [dateFormatter release];
    [gregorianCalendar release];
    [components release];
}