iOS 计算两个日期的间隔

计算两个日期的间隔

+ (NSString *)numberOfDaysWithFromDate:(NSDate *)fromDate toDate:(NSDate *)toDate {
    // 创建一个标准国际时间的日历
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    // 可根据需要自己设置时区.
    calendar.timeZone = myTimeZone;
    // 获取两个日期的间隔
    NSDateComponents *comp = [calendar components:NSCalendarUnitDay|NSCalendarUnitHour fromDate:fromDate toDate:toDate options:NSCalendarWrapComponents];
    NSInteger hour = (comp.hour - comp.day * 24);
    return [NSString stringWithFormat:@"%ld天%ld小时", comp.day, hour];
}

上文中 NSDateComponents 初始化方法中的 components 属性是一个枚举, 还可以获取更多 NSDate 的信息, 配置见下表.

typedef NS_OPTIONS(NSUInteger, NSCalendarUnit) {
        NSCalendarUnitEra                = kCFCalendarUnitEra,
        NSCalendarUnitYear               = kCFCalendarUnitYear,
        NSCalendarUnitMonth              = kCFCalendarUnitMonth,
        NSCalendarUnitDay                = kCFCalendarUnitDay,
        NSCalendarUnitHour               = kCFCalendarUnitHour,
        NSCalendarUnitMinute             = kCFCalendarUnitMinute,
        NSCalendarUnitSecond             = kCFCalendarUnitSecond,
        NSCalendarUnitWeekday            = kCFCalendarUnitWeekday,
        NSCalendarUnitWeekdayOrdinal     = kCFCalendarUnitWeekdayOrdinal,
        NSCalendarUnitQuarter            NS_ENUM_AVAILABLE(10_6, 4_0) = kCFCalendarUnitQuarter,
        NSCalendarUnitWeekOfMonth        NS_ENUM_AVAILABLE(10_7, 5_0) = kCFCalendarUnitWeekOfMonth,
        NSCalendarUnitWeekOfYear         NS_ENUM_AVAILABLE(10_7, 5_0) = kCFCalendarUnitWeekOfYear,
        NSCalendarUnitYearForWeekOfYear  NS_ENUM_AVAILABLE(10_7, 5_0) = kCFCalendarUnitYearForWeekOfYear,
        NSCalendarUnitNanosecond         NS_ENUM_AVAILABLE(10_7, 5_0) = (1 << 15),
        NSCalendarUnitCalendar           NS_ENUM_AVAILABLE(10_7, 4_0) = (1 << 20),
        NSCalendarUnitTimeZone           NS_ENUM_AVAILABLE(10_7, 4_0) = (1 << 21),
};