NSPredicate: filtering objects by day of NSDate property

I have a Core Data model with an NSDate property. I want to filter the database by day. I assume the solution will involve an NSPredicate, but I'm not sure how to put it all together.

I know how to compare the day of two NSDates using NSDateComponents and NSCalendar, but how do I filter it with an NSPredicate?

Perhaps I need to create a category on my NSManagedObject subclass that can return a bare date with just the year, month and day. Then I could compare that in an NSPredicate. Is this your recommendation, or is there something simpler?

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最佳答案

Given a NSDate * startDate and endDate and a NSManagedObjectContext * moc:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(date >= %@) AND (date <= %@)", startDate, endDate];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:[NSEntityDescription entityForName:@"EntityName" inManagedObjectContext:moc]];
[request setPredicate:predicate];


NSError *error = nil;
NSArray *results = [moc executeFetchRequest:request error:&error];
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Example on how to also set up startDate and endDate to the above given answer:

...


NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth ) fromDate:[NSDate date]];
//create a date with these components
NSDate *startDate = [calendar dateFromComponents:components];
[components setMonth:1];
[components setDay:0]; //reset the other components
[components setYear:0]; //reset the other components
NSDate *endDate = [calendar dateByAddingComponents:components toDate:startDate options:0];
predicate = [NSPredicate predicateWithFormat:@"((date >= %@) AND (date < %@)) || (date = nil)",startDate,endDate];


...

Here I was searching for all entries within one month. It's worth to mention, that this example also shows how to search 'nil' date-entires.

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In Swift I got something similar to:

        let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let date = dateFormatter.dateFromString(predicate)
let calendar = NSCalendar(calendarIdentifier: NSGregorianCalendar)
let components = calendar!.components(
NSCalendarUnit.CalendarUnitYear |
NSCalendarUnit.CalendarUnitMonth |
NSCalendarUnit.CalendarUnitDay |
NSCalendarUnit.CalendarUnitHour |
NSCalendarUnit.CalendarUnitMinute |
NSCalendarUnit.CalendarUnitSecond, fromDate: date!)
components.hour = 00
components.minute = 00
components.second = 00
let startDate = calendar!.dateFromComponents(components)
components.hour = 23
components.minute = 59
components.second = 59
let endDate = calendar!.dateFromComponents(components)
predicate = NSPredicate(format: "day >= %@ AND day =< %@", argumentArray: [startDate!, endDate!])

I had a hard time to discover that string interpolation "\(this notation)" doesn't work for comparing dates in NSPredicate.

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For me this is worked.

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit ) fromDate:[NSDate date]];
//create a date with these components
NSDate *startDate = [calendar dateFromComponents:components];
[components setMonth:0];
[components setDay:0]; //reset the other components
[components setYear:0]; //reset the other components
NSDate *endDate = [calendar dateByAddingComponents:components toDate:startDate options:0];


startDate = [NSDate date];
endDate = [startDate dateByAddingTimeInterval:-(7 * 24 * 60 * 60)];//change here


NSString *startTimeStamp = [[NSNumber numberWithInt:floor([endDate timeIntervalSince1970])] stringValue];
NSString *endTimeStamp = [[NSNumber numberWithInt:floor([startDate timeIntervalSince1970])] stringValue];




NSPredicate *predicate = [NSPredicate predicateWithFormat:@"((paidDate1 >= %@) AND (paidDate1 < %@))",startTimeStamp,endTimeStamp];
NSLog(@"predicate is %@",predicate);
totalArr = [completeArray filteredArrayUsingPredicate:predicate];
[self filterAndPopulateDataBasedonIndex];
[self.tableviewObj reloadData];
NSLog(@"result is %@",totalArr);

I have filtered array from current date to 7 days back. I mean I am getting one week data from current date. This should work.

Note: I am converting date which is coming with milli seconds by 1000, and comparing after. Let me know if you need any clarity.

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I ported the answer from Glauco Neves to Swift 2.0 and wrapped it inside a function that receives a date and returns the NSPredicate for the corresponding day:

func predicateForDayFromDate(date: NSDate) -> NSPredicate {
let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)
let components = calendar!.components([.Year, .Month, .Day, .Hour, .Minute, .Second], fromDate: date)
components.hour = 00
components.minute = 00
components.second = 00
let startDate = calendar!.dateFromComponents(components)
components.hour = 23
components.minute = 59
components.second = 59
let endDate = calendar!.dateFromComponents(components)


return NSPredicate(format: "day >= %@ AND day =< %@", argumentArray: [startDate!, endDate!])
}
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I've recently spent some time attempting to solve this same problem and add the following to the list of alternatives to prepare start and end dates (includes updated method for iOS 8 and above)...

NSDate *dateDay = nil;
NSDate *dateDayStart = nil;
NSDate *dateDayNext = nil;


dateDay = <<USER_INPUT>>;


dateDayStart = [[NSCalendar currentCalendar] startOfDayForDate:dateDay];


//  dateDayNext EITHER
dateDayNext = [dateDayStart dateByAddingTimeInterval:(24 * 60 * 60)];


//  dateDayNext OR
NSDateComponents *dateComponentDay = nil;
dateComponentDay = [[NSDateComponents alloc] init];
[dateComponentDay setDay:1];
dateDayNext = [[NSCalendar currentCalendar] dateByAddingComponents:dateComponentDay
toDate:dateDayStart
options:NSCalendarMatchNextTime];

...and the NSPredicate for the Core Data NSFetchRequest (as already shown above in other answers)...

[NSPredicate predicateWithFormat:@"(dateAttribute >= %@) AND (dateAttribute < %@)", dateDayStart, dateDayNext]]
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Adding to Rafael's answer (incredibly useful, thank you!), porting for Swift 3. 

func predicateForDayFromDate(date: Date) -> NSPredicate {
let calendar = Calendar(identifier: Calendar.Identifier.gregorian)
var components = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date)
components.hour = 00
components.minute = 00
components.second = 00
let startDate = calendar.date(from: components)
components.hour = 23
components.minute = 59
components.second = 59
let endDate = calendar.date(from: components)


return NSPredicate(format: "YOUR_DATE_FIELD >= %@ AND YOUR_DATE_FIELD =< %@", argumentArray: [startDate!, endDate!])
}
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Swift 3.0 extension for Date: 

extension Date{


func makeDayPredicate() -> NSPredicate {
let calendar = Calendar.current
var components = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: self)
components.hour = 00
components.minute = 00
components.second = 00
let startDate = calendar.date(from: components)
components.hour = 23
components.minute = 59
components.second = 59
let endDate = calendar.date(from: components)
return NSPredicate(format: "day >= %@ AND day =< %@", argumentArray: [startDate!, endDate!])
}
}

Then use like: 

 let fetchReq = NSFetchRequest(entityName: "MyObject")
fetchReq.predicate = myDate.makeDayPredicate()
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Building on the previous answers, an update and alternative method using Swift 5.x

func predicateForDayUsingDate(_ date: Date) -> NSPredicate {
    

var calendar = Calendar.current
calendar.timeZone = NSTimeZone.local
// following creates exact midnight 12:00:00:000 AM of day
let startOfDay = calendar.startOfDay(for: date)
// following creates exact midnight 12:00:00:000 AM of next day
let endOfDay = calendar.date(byAdding: .day, value: 1, to: startOfDay)!
    

return NSPredicate(format: "day >= %@ AND day < %@", argumentArray: [startOfDay, endOfDay])
}

If you'd prefer to create the time for endOfDay as 11:59:59 PM, you can instead include...

    let endOfDayLessOneSecond = endOfDay.addingTimeInterval(TimeInterval(-1))

but then you might change the NSPredicate to...

    return NSPredicate(format: "day >= %@ AND day <= %@", argumentArray: [startOfDay, endOfDayLessOneSecond])

...with specific note of the change from day < %@ to day <= %@.


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