(Prepare to witness a newbie being very, very confused at what I'd assume is a basic form of logic that my brain is struggling to grasp.)
I have a .plist file at the moment. In the "Key" column there are names of events (it's just dummy content at the moment), and in the "Value" column there are dates in this format: 19-07-2012. Each row is of the "string" type.
In the viewDidLoad method, I use the following code:
NSString *theFile = [[NSBundle mainBundle] pathForResource:#"dates" ofType:#"plist"];
theDates = [[NSDictionary alloc] initWithContentsOfFile:theFile];
theDatesList = [theDates allKeys];
This loads the plist file into the dictionary, then I load the keys into an array, which is the way I've learned to populate a UITableView, specifically with this code in the cellForRowAtIndexPath method:
NSString *eventFromFile = [theDatesList objectAtIndex:indexPath.row];
NSString *dateFromFile = [theDates objectForKey:[theDatesList objectAtIndex:indexPath.row]];
But what I'm confused about now is, how do I order the cells of the UITableView based on what dates are the soonest? So, the cell for the 19th of July would appear before the 21st of August, no matter what order it's in within the plist file.
Within the UITableViewCell I've managed to calculate the number of days between the current date and the date defined within the plist. That's this code:
// Set the date format
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"dd-MM-yyyy"];
// Get the current, then future date
NSDate *currentDate = [NSDate date];
NSDate *futureDate = [dateFormatter dateFromString:dateFromFile];
// Create the calendar object
NSCalendar *theCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
// Extract the "day" component from the calendar object
NSDateComponents *theDifferenceBetweenDays = [theCalendar components:NSDayCalendarUnit
fromDate:currentDate
toDate:futureDate
options:0];
NSInteger theRemainingDays = [theDifferenceBetweenDays day];
But I really have no idea what I'm doing. Could someone give me a nudge in the right direction? I've looked into NSSortDescriptors and the sortedArrayUsingSelector method, which seem to be relevant, but the act of actual implementation has left me stuck for the past six hours. Or maybe they're not the right track. Like I said, I'm quite confused.
Thanks.
There are several ways to sort an NSArray of NSDates in descending order.
You could use sortedArrayUsingDescriptors::
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"self" ascending:NO];
theDatesList = [theDatesList sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
But I personally prefer sortedArrayUsingComparator::
theDatesList = [theDatesList sortedArrayUsingComparator:^NSComparisonResult(NSDate *date1, NSDate *date2){
return [date2 compare:date1];
}];
There exists a objective C equvialent for monotouch.dialog.
with this, it should be really easy.
Related
I'm working with Realm and I have an array sorted by dates for all the entries of a specific card. I need to create a NSPredicate (or some other way) that will give me all the dates for that card in order for a specific month. My trouble is some months have different amounts of days in them.
Here is what I have so far.
// Filter specific card, create date and string for x axis
NSString *filteredName = [NSString stringWithFormat:#"%#", self.cardType];
NSDate *dateElement = [[NSDate alloc]init];
NSString *datedString = [[NSString alloc]initWithFormat:#""];
//Formatting datedString
NSDateFormatter *df = [[NSDateFormatter alloc] init];
df.dateFormat = #"MM/dd/YYYY";
NSSortDescriptor *dateSort = [[NSSortDescriptor alloc]initWithKey:#"date" ascending:YES];
NSArray *sortedArray = #[dateSort];
//self.orderHistory is all of the cards from the Realm database filtered down to a specific type of card.
for (Order *uniqueOrder in [self.orderHistory objectsWhere:#"name = [c] %#", filteredName]) {
// [self.uniqueCardArray addObject:uniqueOrder];
dateElement = uniqueOrder.date;
datedString = [df stringFromDate:dateElement];
[self.uniqueDatesForCardArray addObject:datedString];
}
[self.uniqueCardArray sortUsingDescriptor:sortedArray];
Code above gives me all the dates for a specific card I need the dates for a given month so I have tried this tacky solution but I would think there is something more elegant to say the least.
NSDate *todaysDate = [NSDate date];
NSTimeInterval secondsInMonth =- (60 * 60 * 24 * 365) / 12;
NSDate *dateOneMonthBack = [todaysDate dateByAddingTimeInterval:secondsInMonth];
NSPredicate *backDatesPred = [NSPredicate predicateWithFormat: #"date BETWEEN {%#, %#}", dateOneMonthBack, todaysDate];
Besides it being nasty code it will also take me back a month from the current date and not only back to the start of the month. Been looking at the Realm documentation, NSCalendar stuff, and NSPredicate guide and now my head is swimming trying to count for all the possible problems that can go wrong with this. Any advice or code snippets would be a great help.
I'm not sure whether I understand your question correctly, the following code is what you want?
To determine the date of the previous month, add NSDateComponet that has minus month to the date.
Realm supports BETWEEN query. So you can just query by two days.
NSDate *todaysDate = [NSDate date];
NSDateComponents *comps = [NSDateComponents new];
comps.month = -1;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *dateOneMonthBack = [calendar dateByAddingComponents:comps toDate:todaysDate options:kNilOptions];
RLMResults *filteredHistory = [self.orderHistory objectsWhere:#"name = [c] %#", filteredName];
RLMResults *rangedHistory = [filteredHistory objectsWhere:#"date BETWEEN {%#, %#}", dateOneMonthBack, todaysDate];
I've objects of array, in each object i have different type of strings in one string i am getting date from xml parsing, now my task is that to sort whole data according to time wise(like before date then current date then after date). I am having two problems.
How to sort array on this structure like objects of arrays if simple
then it'll more easy for me?
Which function should I use to sort date wise?
One of several options would be using a comparator block. You didn't provide enough informations, so I made some assumptions:
The date string is at the 3rd index of the NSArrays
The date string looks like 31-12-2011
Code
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:#"dd-MM-yyyy"];
array = [array sortedArrayUsingComparator: ^(id a, id b) {
NSArray *array1 = (NSArray *)a;
NSArray *array2 = (NSArray *)b;
NSDate *date1 = [dateFormatter dateFromString:[array1 objectAtIndex:2]];
NSDate *date2 = [dateFormatter dateFromString:[array2 objectAtIndex:2]];
return [date1 compare:date2]
}
But you should also consider to have an class representing the data.
In that case you would inter ate over the raw dater and create a object for every data set, put it in an NSMutableArray and sort this. similar.
i want to save NSDate from XML to coreData.
I dont know how to set the Value for NSDate. Can someone give me little help?
My Entity attribute is NSDate. Or should it be a String and Save the Date as String??
[Sets setValue:[TBXML textForElement:xmlDate] forKey:#"beginDate"];
Thanks for any response and help,
brush51
Whether you are intentionally obfuscating or not, you don't say it, so I'm going to guess that:
[TBXML textForElement:xmlDate] returns an NSString
beginDate is a Date property of entity Sets
In which case your code is obviously incorrect: you must pass an instance of NSDate to setValue:forKey:. Your code would look like:
NSDateFormatter *myXMLdateReader = [[NSDateFormatter alloc] init];
[myXMLdateReader setDateFormat:#"yyyy-MM-dd"]; // for example
NSDate *itsDate = [myXMLdateReader dateFromString:[TBXML textForElement:xmlDate]];
[myXMLdateReader release];
[Sets setValue:itsDate forKey:#"beginDate"];
It is no problem to add NSDate to CoreData. All you need to do is to convert NSString from XML file to NSDate object. For converting NSString <-> NSDate you can use NSDateFormatter class. In example below you can see how I do this:
NSDateFormatter *parseFormatter = [[[NSDateFormatter alloc] init] autorelease];
[parseFormatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:#"US"] autorelease]];
[parseFormatter setDateFormat:#"EEE, dd MMM yyyy HH:mm:ss Z"];
NSString *dateString = #"Mon, 02 May 2011 21:12:56 +0000";
NSDate *dateToAdd = [parser.parseFormatter dateFromString:dateString];
You can set needful date format and use this code in your project.
I have a function that returns an array to hold date info.
- (NSArray*) getTodayArray
{
NSDate *today = [NSDate date];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"YYYY"];
NSString *year = [dateFormatter stringFromDate:today];
[dateFormatter setDateFormat:#"MM"];
NSString *month = [dateFormatter stringFromDate:today];
[dateFormatter release];
NSArray *res = [NSArray arrayWithObjects: year, month, nil];
return res;
}
Q1 : Is there any easy way to get all the info (year, month, date, hour, minute ...) in an array not using setDateFormat over and over again?
Q2 : Is there a way so that I can access the content of array using res['year'] or similar? I mean using dictionary?
Q3 : Do I need to release NSArray *res in the caller of this function?
A1: You can do smth like this:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"YYYY|MM"];
NSArray* d_arr = [[dateFormatter stringFromDate: [NSDate date]] componentsSeparatedByString: #"|"];
A2: Use NSDictionary:
[NSDictionary dictionaryWithObjectsAndKeys: [d_arr objectAtIndex: 0], #"year", [d_arr objectAtIndex: 1], #"month", nil]
A3: return value is autoreleased. you don't need to release it.
#prosseek
1 - I dont think you have another choice to get the year, month, date, hour, minute ... from NSDate other than this.(I am not sure about it though.)
2 - you can access the objects in the dictionary in the above format but something more like objective-c style. like this
[dateDictionary obectForKey:#"year"];
but you need to define the dictionary in that format
like this
NSDictionary *dateDictionary = [NSDictionary dictionaryWithObjects:year,min,hr,nil forKeys:#"year", #"min", #"hour", nil];
3 - no you dont need to release or autorelease the NSArray in the above method . but i think you need to retain it in the array that is receiving res array if you want to use it after a while.
Why don't you just use a NSArray of NSDates?
You can probably get all of your desired functionality out of its plethora of functions.
A1: You could dump it all out into a string, but then you'd have to parse the string, which wouldn't be any easier.
A2: You could do that if you used an NSDictionary instead of an NSArray.*
A3: No, it's already autoreleased.
* Why don't you write a category for NSDate instead?
NSDate+Convenience.h
#interface NSDate (Convenience)
- (NSInteger)year;
- (NSInteger)month;
#end
NSDate+Convenience.m
#implementation NSDate (Convenience)
- (NSInteger)year {
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"YYYY"];
NSString *myYear = [dateFormatter stringFromDate:self];
[dateFormatter release];
return myYear;
}
- (NSInteger)month {
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"MM"];
NSString *myMonth = [dateFormatter stringFromDate:self];
[dateFormatter release];
return myMonth;
}
#end
Just #include NSDate+Convenience.h wherever you want to use your handy date and month accessors. All of your NSDate instances will then get them:
NSDate *myDate = [NSDate date];
NSLog(#"%ld %ld", [myDate year], [myDate month]);
No need for loosely-typed NSArrays or NSDictionaries to store this stuff.
(Note you could modify the above code to use a shared NSDateFormatter.)
Q1: Not an array, but you can use -[NSCalendar components:fromDate:] to get an NSDateComponents object. You can use it directly or build an array from it, if that is your preference.
Q2: No, but if you return an NSDateComponents object, then you can use -year, -month, etc methods on it.
Q3: No, you don't need to release it in this method or the caller, unless the caller retains it (which may be desirable).
You're looking for the NSDateComponents class. You'll need to create an NSCalendar object first, then call the components:fromDate: method to get the DateComponents object, after which you can access the object's month, year etc. properties.
Not quite sure what you want here. As it stands, the array cannot be accessed in the manner you describe, though if you want you could always create a dictionary and assign values for keys such as 'month' or 'year'. However, it might just be easier to return the DateComponents object, and access its properties.
No, there is no need to release the NSArray. You constructed it using the NSArray class method, which is already autoreleased.
I have an NSArray that contains date strings (i.e. NSString) like this: "Thu, 21 May 09 19:10:09 -0700"
I need to sort the NSArray by date. I thought about converting the date string to an NSDate object first, but got stuck there on how to sort by the NSDate object.
Thanks.
If I have an NSMutableArray of objects with a field "beginDate" of type NSDate I am using an NSSortDescriptor as below:
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"beginDate" ascending:TRUE];
[myMutableArray sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
Store the dates as NSDate objects in an NS(Mutable)Array, then use -[NSArray sortedArrayUsingSelector: or -[NSMutableArray sortUsingSelector:] and pass #selector(compare:) as the parameter. The -[NSDate compare:] method will order dates in ascending order for you. This is simpler than creating an NSSortDescriptor, and much simpler than writing your own comparison function. (NSDate objects know how to compare themselves to each other at least as efficiently as we could hope to accomplish with custom code.)
You may also use something like the following:
//Sort the array of items by date
[self.items sortUsingComparator:^NSComparisonResult(id obj1, id obj2){
return [obj2.date compare:obj1.date];
}];
But this does assume that the date is stored as a NSDate rather a NString, which should be no problem to make/do. Preferably, I recommend also storing the data in it's raw format. Makes it easier to manipulate in situations like this.
You can use blocks to sort in place:
sortedDatesArray = [[unsortedDatesArray sortedArrayUsingComparator: ^(id a, id b) {
NSDate *d1 = [NSDate dateWithString: s1];
NSDate *d2 = [NSDate dateWithString: s2];
return [d1 compare: d2];
}];
I suggest you convert all your strings to dates before sorting not to do the conversion more times than there are date items. Any sorting algorithm will give you more string to date conversions than the number of items in the array (sometimes substantially more)
a bit more on blocks sorting: http://sokol8.blogspot.com/2011/04/sorting-nsarray-with-blocks.html
What it worked in my case was the following:
NSArray *aUnsorted = [dataToDb allKeys];
NSArray *arrKeys = [aUnsorted sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:#"dd-MM-yyyy"];
NSDate *d1 = [df dateFromString:(NSString*) obj1];
NSDate *d2 = [df dateFromString:(NSString*) obj2];
return [d1 compare: d2];
}];
I had a dictionary, where all keys where dates in format dd-MM-yyyy. And allKeys returns the dictionary keys unsorted, and I wanted to present the data in chronological order.
You can use sortedArrayUsingFunction:context:. Here is a sample:
NSComparisonResult dateSort(NSString *s1, NSString *s2, void *context) {
NSDate *d1 = [NSDate dateWithString:s1];
NSDate *d2 = [NSDate dateWithString:s2];
return [d1 compare:d2];
}
NSArray *sorted = [unsorted sortedArrayUsingFunction:dateSort context:nil];
When using a NSMutableArray, you can use sortArrayUsingFunction:context: instead.
Once you have an NSDate, you can create an NSSortDescriptor with initWithKey:ascending: and then use sortedArrayUsingDescriptors: to do the sorting.
Swift 3.0
myMutableArray = myMutableArray.sorted(by: { $0.date.compare($1.date) == ComparisonResult.orderedAscending })
Change this
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"beginDate" ascending:TRUE];
[myMutableArray sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
To
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"Date" ascending:TRUE];
[myMutableArray sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
Just change the KEY: it must be Date always