Objective-C中的模糊数据算法

Question

我想写一个模糊日期方法来计算iPhone的Objective-C中的日期.这里有一个流行的解释:

计算C#中的相对时间

但它包含缺少的参数.怎么能在Objective-C中使用它？谢谢.

const int SECOND = 1;
const int MINUTE = 60 * SECOND;
const int HOUR = 60 * MINUTE;
const int DAY = 24 * HOUR;
const int MONTH = 30 * DAY;

if (delta < 1 * MINUTE)
{
  return ts.Seconds == 1 ? "one second ago" : ts.Seconds + " seconds ago";
}
if (delta < 2 * MINUTE)
{
  return "a minute ago";
}
if (delta < 45 * MINUTE)
{
  return ts.Minutes + " minutes ago";
}
if (delta < 90 * MINUTE)
{
  return "an hour ago";
}
if (delta < 24 * HOUR)
{
  return ts.Hours + " hours ago";
}
if (delta < 48 * HOUR)
{
  return "yesterday";
}
if (delta < 30 * DAY)
{
  return ts.Days + " days ago";
}
if (delta < 12 * MONTH)
{
  int months = Convert.ToInt32(Math.Floor((double)ts.Days / 30));
  return months <= 1 ? "one month ago" : months + " months ago";
}
else
{
  int years = Convert.ToInt32(Math.Floor((double)ts.Days / 365));
  return years <= 1 ? "one year ago" : years + " years ago";
}

Answer 1

使用NSDate该类在Cocoa中表示日期.有一种方便的方法NSDate可以获得两个日期实例之间的增量,以秒为单位timeIntervalSinceDate:.这是在一个NSDate实例上调用的,将另一个NSDate对象作为参数.它返回一个NSTimeInterval(这是double的typedef),它代表两个日期之间的秒数.

鉴于此,将上面给出的代码调整为Objective-C/Cocoa上下文会相当简单.由于计算的delta NSDate以秒为单位给出,给定两个日期,您可以轻松调整上面的代码:

//Constants
#define SECOND 1
#define MINUTE (60 * SECOND)
#define HOUR (60 * MINUTE)
#define DAY (24 * HOUR)
#define MONTH (30 * DAY)

- (NSString*)timeIntervalWithStartDate:(NSDate*)d1 withEndDate:(NSDate*)d2
{
    //Calculate the delta in seconds between the two dates
    NSTimeInterval delta = [d2 timeIntervalSinceDate:d1];

    if (delta < 1 * MINUTE)
    {
        return delta == 1 ? @"one second ago" : [NSString stringWithFormat:@"%d seconds ago", (int)delta];
    }
    if (delta < 2 * MINUTE)
    {
        return @"a minute ago";
    }
    if (delta < 45 * MINUTE)
    {
        int minutes = floor((double)delta/MINUTE);
        return [NSString stringWithFormat:@"%d minutes ago", minutes];
    }
    if (delta < 90 * MINUTE)
    {
        return @"an hour ago";
    }
    if (delta < 24 * HOUR)
    {
        int hours = floor((double)delta/HOUR);
        return [NSString stringWithFormat:@"%d hours ago", hours];
    }
    if (delta < 48 * HOUR)
    {
        return @"yesterday";
    }
    if (delta < 30 * DAY)
    {
        int days = floor((double)delta/DAY);
        return [NSString stringWithFormat:@"%d days ago", days];
    }
    if (delta < 12 * MONTH)
    {
        int months = floor((double)delta/MONTH);
        return months <= 1 ? @"one month ago" : [NSString stringWithFormat:@"%d months ago", months];
    }
    else
    {
        int years = floor((double)delta/MONTH/12.0);
        return years <= 1 ? @"one year ago" : [NSString stringWithFormat:@"%d years ago", years];
    }
}

然后调用它,将start和end NSDate对象作为参数传递,并返回一个NSString时间间隔.