How to verify today date with last CoreData entry - ios

Question

I have a CoreData attributes that 2 (value, date). When I click on a UIButton, it added an entry corresponding to the value of the UIButton.
I will wish to limit the addition of entry to a daily. Basically, I will wish to check the current date and the date of the last entry. If it's value are identical, this is not added.
My Function
func data(sender: UIButton) {
// Date Format
let date = NSDate()
let formatter = NSDateFormatter()
formatter.dateFormat = "YYYY/MM/dd"
let dateFormat = formatter.stringFromDate(date)
// Load Entity
let AppDel : AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let theContext : NSManagedObjectContext = AppDel.managedObjectContext
let theEnt = NSEntityDescription.entityForName("Mood", inManagedObjectContext: theContext)
// Create Item
let newItem = Mood(entity: theEnt!, insertIntoManagedObjectContext: theContext)
newItem.mood = String(sender.tag)
newItem.date = dateFormat
// Save Item
do {
try theContext.save()
} catch _ {
}
}
Thank you in advance for your response.

Answer 1

If you fetch the Mood objects, sorted by date in descending order, the first item returned will be the last entry. You can set the fetchLimit to 1 to avoid loading more objects than are necessary. You can then test to see whether the date attribute matches, and handle accordingly:
func data(sender: UIButton) {
// Date Format
let date = NSDate()
let formatter = NSDateFormatter()
formatter.dateFormat = "YYYY/MM/dd"
let dateFormat = formatter.stringFromDate(date)
// Get context and entity details
let AppDel : AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let theContext : NSManagedObjectContext = AppDel.managedObjectContext
let theEnt = NSEntityDescription.entityForName("Mood", inManagedObjectContext: theContext)
// Fetch the latest entry
let fetch = NSFetchRequest()
fetch.entity = theEnt!
let sort = NSSortDescriptor(key: "date", ascending:false)
fetch.sortDescriptors = [sort]
fetch.fetchLimit = 1
let results = try! theContext.executeFetchRequest(fetch) as! [Mood]
// NB should do proper try/catch error checking
// Check for existing entry
if (results.count > 0) {
// Check whether date matches
if (results[0].date != dateFormat) {
let newItem = Mood(entity: theEnt!, insertIntoManagedObjectContext: theContext)
newItem.mood = String(sender.tag)
newItem.date = dateFormat
}
} else { // No entries yet, I assume you want to add one...
let newItem = Mood(entity: theEnt!, insertIntoManagedObjectContext: theContext)
newItem.mood = String(sender.tag)
newItem.date = dateFormat
}
// Save Item
do {
try theContext.save()
} catch _ {
}
}
Note that (given your code newItem.date = dateFormat) I am assuming the date attribute is a string which you set using the same format ("YYYY/MM/dd"). This strips out the time information and so avoids the need for the date comparisons, but also has the advantage that a string sort is equivalent to a date sort (perhaps you chose that format for that reason). If date is in fact a Date attribute, the sort will still work but you will need to use a date comparison.

Answer 2

I use an NSDate extension for this.
extension NSDate {
class func areDatesSameDay(dateOne:NSDate,dateTwo:NSDate) -> Bool {
let calender = NSCalendar.currentCalendar()
let flags: NSCalendarUnit = [.Day, .Month, .Year]
let compOne: NSDateComponents = calender.components(flags, fromDate: dateOne)
let compTwo: NSDateComponents = calender.components(flags, fromDate: dateTwo);
return (compOne.day == compTwo.day && compOne.month == compTwo.month && compOne.year == compTwo.year);
}
}
Usage is like this.
if NSDate.areDatesSameDay(dateOne, dateTwo: dateTwo) {
// Dates are same day
} else {
// Dates are not the same day
}
#Tom Harrington Has just pointed out that you can use the NSCalendar methods to do this more simply
let calender = NSCalendar.currentCalendar()
if calender.isDate(dateOne, inSameDayAsDate: dateTwo) {
// Dates are same day
}
So we can make my lovely extension even simpler...
extension NSDate {
func isSameDayAs(date:NSDate) -> Bool {
let calender = NSCalendar.currentCalendar()
return calender.isDate(self, inSameDayAsDate: date)
}
}
Then use it like this.
if dateOne.isSameDayAs(dateTwo) {
// Dates are same day
} else {
// Dates are not the same day
}
And thats Numberwang!