獲取時間間隔

- (NSInteger)getDifferenceByDate:(NSString
 *)date {
    
//獲得當前時間

    
NSDate *now = [NSDate date
];
    
//實例化一個NSDateFormatter對象

    
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init
];
    
//設定時間格式

    [dateFormatter 
setDateFormat:@"yyyy-MM-dd HH:mm:ss"
];
    
NSDate *oldDate = [dateFormatter dateFromString
:date];
    
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar
];
    
unsigned int unitFlags = NSDayCalendarUnit
;
    
NSDateComponents *comps = [gregorian components:unitFlags fromDate:oldDate  toDate:now  options:0
];
    
return [comps day
];
}