ios - UITableView 滚动到最接近今天日期的部分

Question

我有一个 tableview，里面有一个日历，里面有约会。每一天都是一个单独的部分。你可以在这里明白我的意思

现在，我希望 tableview 滚动到今天的 section，或者如果今天没有 section，则滚动到最接近的 section。

我知道我应该使用以下代码:

 [tableView scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];

现在我有一个 NSMutableDictionary 包含我排序的约会/天。你可以看到下面的功能:

-(NSDictionary *)sortKalendar:(NSMutableArray *)appointments{
    NSMutableDictionary *buffer = [[NSMutableDictionary alloc] init];

    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"dd-MM-yyyy"];

    for (int i = 0; i < appointments.count; i++) {
        Appointment *object = [appointments objectAtIndex:i];
        NSString *date = [formatter stringFromDate:object.app_start];
        if(!(date == NULL) ){
            NSLog(@"date is %@",date);
            if ([buffer objectForKey:date]) {
                [(NSMutableArray *)[buffer objectForKey:date] addObject:object];
            } else {
                NSMutableArray *mutableArray = [[NSMutableArray alloc] initWithObjects:object, nil];
                [buffer setObject:mutableArray forKey:date];
            }
        }


    }
    NSDictionary *result = [NSDictionary dictionaryWithDictionary:buffer];

    return result;
}

我现在的问题是，我怎样才能找到正确的 NSIndexpath ？

提前致谢!

编辑

目前我正在使用以下内容。但是还是有些不对。

NSArray *keys = [dictAppointments allKeys];

NSLog(@"KEYS ARE %@",keys)  ;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd-MM-yyyy"];

NSArray *sortedArray = [keys sortedArrayUsingComparator:^(id obj1, id obj2) {
    NSDate *date1 = [formatter dateFromString:obj1];
    NSDate *date2 = [formatter dateFromString:obj2];

    NSNumber *interval1 = [NSNumber numberWithDouble:[date1 timeIntervalSinceNow]];
    NSNumber *interval2 = [NSNumber numberWithDouble:[date2 timeIntervalSinceNow]];
    return (NSComparisonResult)[interval1 compare:interval2];
}];
NSLog(@"Sorted Array %@",sortedArray);
NSString *closestDateString = [sortedArray objectAtIndex:0];
NSLog(@"Closest date string is %@",closestDateString);
int section = [keys indexOfObject:closestDateString];
NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:0 inSection:section];
[tableView scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];

这给了我以下日志:

2014-01-07 13:28:42.420 Adsolut[9579:60b] KEYS ARE (
    "03-12-2013",
    "20-12-2013",
    "17-12-2013",
    "05-01-2014",
    "21-12-2013",
    "31-12-2013",
    "04-01-2014",
    "06-01-2014",
    "16-01-2014",
    "29-12-2013",
    "03-01-2014",
    "11-01-2014",
    "18-12-2013",
    "31-01-2014"
)
2014-01-07 13:28:42.437 Adsolut[9579:60b] Sorted Array (
    "03-12-2013",
    "17-12-2013",
    "18-12-2013",
    "20-12-2013",
    "21-12-2013",
    "29-12-2013",
    "31-12-2013",
    "03-01-2014",
    "04-01-2014",
    "05-01-2014",
    "06-01-2014",
    "11-01-2014",
    "16-01-2014",
    "31-01-2014"
)

Answer 1

您可以使用约会日期和当前日期之间的时间间隔对数组进行排序，

NSArray *keys = [yourDictionary allKeys];

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd-MM-yyyy"];

NSArray *sortedArray = [keys sortedArrayUsingComparator:^(id obj1, id obj2) {
    NSDate *date1 = [formatter dateFromString:obj1];
    NSDate *date2 = [formatter dateFromString:obj2];

    NSNumber *interval1 = [NSNumber numberWithDouble:abs([date1 timeIntervalSinceNow])];
    NSNumber *interval2 = [NSNumber numberWithDouble:abs([date2 timeIntervalSinceNow])];
    return (NSComparisonResult)[interval1 compare:interval2];
}];

最近的日期，

NSString *closestDateString = [sortedArray objectAtIndex:0];

从那开始，

int section = [keys indexOfObject:closestDateString];
NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:0 inSection:section];