如何通过使用两个不同的日期选择器找到两个日期之间的差异

Question

i did a code to find difference between two dates using two different date pickers. i couldn't find the difference between two dates. the difference of two dates is always zero.

@property (strong, nonatomic) IBOutlet UILabel *date1;
@property (strong, nonatomic) IBOutlet UILabel *date2;
- (IBAction)cale1:(id)sender;
- (IBAction)cale2:(id)sender;
@property (strong, nonatomic) IBOutlet UIDatePicker *datePicker1;
@property (strong, nonatomic) IBOutlet UIDatePicker *datePicker2;
@property NSDate *d1,*d2;

@implementation ViewController

- (IBAction)cale1:(id)sender {
    NSDateFormatter *dc=[[NSDateFormatter alloc]init];
    dc.dateStyle=NSDateFormatterFullStyle;
    _d1=_datePicker1.date;
    _date1.text=[dc stringFromDate:_datePicker1.date];
    NSLog(@"Date %@",_date1);
}

- (IBAction)cale2:(id)sender {
    NSDateFormatter *dc=[[NSDateFormatter alloc]init];
    dc.dateStyle=NSDateFormatterFullStyle;
   _d2=_datePicker2.date;
    _date2.text=[dc stringFromDate:_datePicker2.date];
    NSLog(@"Date %@",_d2);

    [self isSameDay:_d1 otherDay:_d2];

}
-(BOOL)isSameDay:(NSDate *)date1 otherDay:(NSDate *)date2{
    NSCalendar *cale=[NSCalendar currentCalendar];
    unsigned unitFlags=NSYearCalendarUnit| NSMonthCalendarUnit| NSDayCalendarUnit;
    NSDateComponents *comp1=[cale components:unitFlags fromDate:date1];
    NSDateComponents *comp2=[cale components:unitFlags fromDate:date2];


   // NSString *comp=[NSString stringWithFormat:@"%d", [comp1 day]==[comp2 day]&&[comp1 month]==[comp2 month]&&[comp1 year]==[comp2 year]];
    BOOL a=[comp1 day]==[comp2 day]&&[comp1 month]==[comp2 month]&&[comp1 year]==[comp2 year];

    NSLog(@"Date Differ%hhd",a);
    return a;
}

Answer 1

Are the dates that are in the compare method valid dates?

If they are you can just do:

BOOL difference = [date1 timeIntervalSinceDate:date2] > 0; 

Difference will be true if the dates are not the same. timeIntervalSinceDate returns NSTimeInterval which is:

Used to specify a time interval, in seconds.

Answer 2

For comparing two dates you need to use the NSDateComponents.I modified your function "isSameDay". It returns the number of day differences between two dates.

-(int)isSameDay:(NSDate *)date1 otherDay:(NSDate *)date2
{    
    NSDateComponents *components;

    int days;

    components = [[NSCalendar currentCalendar] components: NSDayCalendarUnit
                                             fromDate: date1 toDate: date2 options: 0];
    days = (int) [components day];

    NSLog(@"days %d",abs(days));

    return days;

}