Comparing uipickerdate to current date - ios

Question

Here is the code that I have for my two datepickers which I need to compare them to the current date with an if condition or a switch.
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
dateFormatter.timeZone=[NSTimeZone defaultTimeZone];
dateFormatter.timeStyle=NSDateFormatterShortStyle;
dateFormatter.dateStyle=NSDateFormatterShortStyle;
NSString *dateTimeString=[dateFormatter stringFromDate:startTime.date];
NSLog(#"Start time is %#",dateTimeString);
NSDateFormatter *dateFormatter2 = [[NSDateFormatter alloc]init];
dateFormatter2.timeZone=[NSTimeZone defaultTimeZone];
dateFormatter2.timeStyle=NSDateFormatterShortStyle;
dateFormatter2.dateStyle=NSDateFormatterShortStyle;
NSString *dateTimeString2=[dateFormatter2 stringFromDate:endTime.date];
NSLog(#"End time is %#",dateTimeString2);
in my .h
#property (weak, nonatomic) IBOutlet UIDatePicker *startTime;
#property (weak, nonatomic) IBOutlet UIDatePicker *endTime;
How do I do that? Do I need to store them to an NSDate or NSTime since I only really need the time?
Also, is there an If range in Objective C?
Thanks,

Answer 1

Just add this:
if ([[NSDate date] isEqualToDate:startTime.date]) {
NSLog(#"currentDate is equal to startTime");
}
if ([[NSDate date] isEqualToDate:endTime.date]) {
NSLog(#"currentDate is equal to endTime");
}
If you want to calculate interval between two dates use this method
- (NSTimeInterval)timeIntervalSinceDate:(NSDate *)anotherDate
if([startTime.date timeIntervalSinceDate:[NSDate date]] > 0)
{
//start time greater than today
}
else if([startTime.date timeIntervalSinceDate:[NSDate date]] < 0)
{
//start time less than today
}
else
{
//both dates are equal
}
For knowing when the application has entered background use notifications add this statement in your viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(applicationEnteredBackground) name:UIApplicationDidEnterBackgroundNotification object:nil];
Add function to cater the notification when it is posted
-(void)applicationEnteredBackground
{
//do all the above steps here when you want.
}
And in dealloc function of the class remove observer for notification
-(void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

Answer 2

The only dates I see in your code are startTime.date and endTime.date. I don't know where you are getting those, but they are presumably NSDates. The current date, on the other hand, is [NSDate date]. Hence you can compare using NSDate's compare: method or any of several other comparison methods (see the NSDate documentation).

Answer 3

NSDate implements isEqualToDate: which tests if two dates are the same down to the microsecond. It also implements earlierDate: and laterDate: which you can use to build a range check.
You could also build some helpers that let you control the sensitivity of equality check using timeIntervalSinceDate:. There's no date range object, but you could add a between check to your helpers, too...
#interfce NSDate (Comparison)
- (BOOL)isEqualToDate:(NSDate *)aDate within:(NSTimeInterval)tolerance;
- (BOOL)isBetween:(NSDate *)start and:(NSDate *)end within:(NSTimeInterval)tolerance;
#end
#implementation NSDate (Comparison)
- (BOOL)isEqualToDate:(NSDate *)aDate within:(NSTimeInterval)tolerance {
NSTimeInterval difference = [self timeIntervalSinceDate:aDate];
return fabs(difference) < tolerance;
}
- (BOOL)isBetween:(NSDate *)start and:(NSDate *)end within:(NSTimeInterval)tolerance {
NSTimeInterval startDifference = [self timeIntervalSinceDate:start];
if (startDifference < tolerance) return NO;
NSTimeInterval endDifference = [end timeIntervalSinceDate:self];
if (endDifference < tolerance) return NO;
return YES;
}
#end
I haven't tested these.

Answer 4

you can also do like below by using NSDate's compare: method,
NSDateFormatter* df = [[NSDateFormatter alloc] init];
[df setDateFormat:#"MM-dd-yyyy"];
NSDate* date1 = [df dateFromString:#"12-23-2046"];
NSDate *date2 = [NSDate date];
if ([date1 compare:date2] == NSOrderedSame){
NSLog(#"Same");
}
if ([date2 compare:date1]==NSOrderedAscending ) {
NSLog(#"AScending");
}
if ([date2 compare:date1]== NSOrderedDescending) {
NSLog(#"Descending");
}
take your startTime,endTime instead of date1,hope it will helps you.