I am quite new to ios and I was wondering how one could from a NSMutableArray of dates ( as strings) extract all the sundays in that array.
So far from my research I found that I have to start from the date of today like this
NSDate *now = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
Then "select" the sundays like that
NSDateComponents *dateComponents = [calendar components:NSWeekdayCalendarUnit | NSHourCalendarUnit fromDate:now];
NSInteger weekday = [dateComponents 1]; // 1 is sunday right ?!
Then go back into the past and every sunday put the date in a new array or else.
NSDate *dateRelease;
NSDateFormatter *dateFormatter = [ [ NSDateFormatter alloc ] init ];
[ dateFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"UTC"] ];
[ dateFormatter setDateFormat:#"yyyy-MM-dd" ];
for (int i = [ dateFormatter dateFromString:[[[[DessinsManager sharedInstance]imagesList].count ; i > 0; i--){
dateRelease = [ dateFormatter dateFromString:[[[[DessinsManager sharedInstance]imagesList] objectAtIndex:i]dateDrawing] ];
//Check for the sundays here
if ( [now compare: dateRelease] == NSOrderedDescending ) {
//if sundays put in new array
} else {
//if not sundays then go on with loop
}
}
And for this I am a bit confused on how to do the comparaison to get the sundays (my array goes from november 1st 2013 till today)...
Thanks for your help
V.v
First store the dates as NSDate objects as you should always store data using the most appropriate data type:
NSArray *datesAsStrings = ...;
NSMutableArray *dates = [NSMutableArray new];
NSDateFormatter *dateFormatter = [NSDateFormatter new];
dateFormatter.timeZone = [NSTimeZone timeZoneWithAbbreviation:#"UTC"];
dateFormatter.dateFormat = #"yyyy-MM-dd";
for (NSString *dateStr in datesAsStrings) {
NSDate *date = [dateFormatter dateFromString:dateStr];
[dates addObject:dates];
}
and then filter out the sundays:
NSMutableArray *sundays = [NSMutableArray new];
[dates enumerateObjectsUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop)) {
NSDate *date = (NSDate *)obj;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *comps = [calendar components:NSWeekdayCalendarUnit
fromDate:date];
if (comps.weekday == 1)
[sundays addObject:date];
}];
You should be using the - (NSArray *)filteredArrayUsingPredicate:(NSPredicate *)predicate method, which returns a new array evaluating each object in the original one with a predicate.
Such a predicate may be built with + (NSPredicate *)predicateWithBlock:(BOOL (^)(id evaluatedObject, NSDictionary *bindings))block and maybe some inspiration from Dave DeLong's answer here to recognise the day being evaluated.
Related
I am trying to get all dates in the current week of a given date:
In the example below, the input is
2015-11-29 23:40:37 +0000
, so I would expect the output to be an array of dates from November 23 - November 29, but the actual output is November 30 - December 6.
-(NSArray *)datesForWeekOf : (NSDate *) date {
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *startOfWeek;
NSDate *endOfWeek;
NSTimeInterval interval;
[calendar rangeOfUnit:NSCalendarUnitWeekOfMonth startDate:&startOfWeek interval:&interval forDate:date];
endOfWeek = [startOfWeek dateByAddingTimeInterval:interval-1];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSCalendarIdentifierGregorian];
NSDateComponents *days = [[NSDateComponents alloc] init];
NSInteger dayCount = 0;
NSMutableArray *allDates = [NSMutableArray array];
while ( TRUE ) {
[days setDay: ++dayCount];
NSDate *date = [gregorianCalendar dateByAddingComponents: days toDate: startOfWeek options: 0];
[allDates addObject:date];
if ( [date compare: endOfWeek] == NSOrderedDescending )
break;
}
return allDates;
}
You can get all dates of this week and next week using following code:-
NSArray * allDatesOfThisWeek = [self daysThisWeek];
NSArray * allDatesOfNextWeek = [self daysNextWeek];
Following methods are used for calculating dates of this week:-
-(NSArray*)daysThisWeek
{
return [self daysInWeek:0 fromDate:[NSDate date]];
}
-(NSArray*)daysNextWeek
{
return [self daysInWeek:1 fromDate:[NSDate date]];
}
-(NSArray*)daysInWeek:(int)weekOffset fromDate:(NSDate*)date
{
NSCalendar *calendar = [NSCalendar currentCalendar];
//ask for current week
NSDateComponents *comps = [[NSDateComponents alloc] init];
comps=[calendar components:NSWeekCalendarUnit|NSYearCalendarUnit fromDate:date];
//create date on week start
NSDate* weekstart=[calendar dateFromComponents:comps];
NSDateComponents* moveWeeks=[[NSDateComponents alloc] init];
moveWeeks.weekOfYear=weekOffset;
weekstart=[calendar dateByAddingComponents:moveWeeks toDate:weekstart options:0];
//add 7 days
NSMutableArray* week=[NSMutableArray arrayWithCapacity:7];
for (int i=1; i<=7; i++) {
NSDateComponents *compsToAdd = [[NSDateComponents alloc] init];
compsToAdd.day=i;
NSDate *nextDate = [calendar dateByAddingComponents:compsToAdd toDate:weekstart options:0];
[week addObject:nextDate];
}
return [NSArray arrayWithArray:week];
}
If you want to get dates of next to next week from today, then pass weekOffset=2 like this:-
NSArray * allDatesOfNextToNextWeek = [self daysInWeek:2 fromDate:now];
If you want to get dates of previous week from today, then pass weekOffset=-1 like this:-
NSArray * allDatesOfPreviousWeek = [self daysInWeek:-1 fromDate:now];
Hope, this is what you're looking for. Any concern get back to me.
I have found the below code online for comparing two dates (the date of the calendar and some another date) what I would like help with is modifying this code so that it compares the calendar date with the date of an event where date here is key for each event within NSArray (json file) .. Also how I could use this later with NSPredicate so that I can load only the events with components (difference between two dates in days) at least more than 1 day since Im going to have UIButton called future events when the user click on it, all the future events should be loaded .. I would really appreciate any help and code examples since Im very new to objective C and Xcode. Thanks.
#implementation HomeViewController {
NSArray *_events;
}
- (BOOL)isSameDay:(NSDate*)date
{
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDate *currDate = [NSDate date];
//date = [_events objectAtIndex:date];
unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
NSDateComponents* comp1 = [calendar components:unitFlags fromDate:date];
NSDateComponents* comp2 = [calendar components:unitFlags fromDate:currDate];
NSDateComponents *components = [calendar components:unitFlags
fromDate:currDate
toDate:date
options:0];
NSLog(#"Days between dates: %#", components);
return [comp1 day] == [comp2 day] &&
[comp1 month] == [comp2 month] &&
[comp1 year] == [comp2 year];
}
To get the number of days remaining for a date from now, you can use the method below:
-(long)daysRemaining:(NSDate*) date
{
NSDate *now = [NSDate date];
NSTimeInterval dateDiff = [date timeIntervalSinceNow] - [now timeIntervalSinceNow];
CGFloat numberOfDaysRemaining = (dateDiff/(60*60*24));
return ceil(numberOfDaysRemaining);
}
So you can call to get the number of days remaining like this:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"yyyy-MM-dd"];
NSDate *dateToCompare = [dateFormatter dateFromString: #"2014-02-08"];
long numberDays = [self daysRemaining:dateToCompare];
For this case, the result is 2 days remaining. Note that a negative result indicates that was passed n days.
To filter the array (2 days remaining events) making a copy of it:
NSArray* dates = [[NSArray alloc] initWithObjects:
[dateFormatter dateFromString: #"2014-02-08"],
[dateFormatter dateFromString: #"2014-02-05"],
[dateFormatter dateFromString: #"2014-02-10"],
[dateFormatter dateFromString: #"2014-02-08"], nil];
NSArray *filteredArray = [dates filteredArrayUsingPredicate:
[NSPredicate predicateWithBlock:
^BOOL(id evaluatedObject, NSDictionary *bindings) {
long daysRemaining = [self daysRemaining:(NSDate*)evaluatedObject];
return daysRemaining == 2; // if someMethod returns YES, the object is kept
}
]];
To filter an NSMutableArray in place:
[mutableArray filterUsingPredicate:[NSPredicate predicateWithBlock:
^BOOL(id evaluatedObject, NSDictionary *bindings) {
long daysRemaining = [self daysRemaining:(NSDate*)evaluatedObject];
return daysRemaining == 2; // if someMethod returns YES, the object is kept
}
]];
[displayedEvents addObjectsFromArray:[_events filteredArrayUsingPredicate:
[NSPredicate predicateWithBlock:
^BOOL(Events * event, NSDictionary *bindings) {
[dateFormatter dateFromString: event.date];
long daysRemaining = [self daysRemaining: (NSDate*)event.date];
return daysRemaining > 1; // if someMethod returns YES, the object is kept
}
]]];
I want to get day parts from a date interval.
For example I have a date interval 21/12/2013 to 28/12/2013.
Now I want to get all day part from this interval like as 21,22,23,24,25,26,27,28.
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:#"GMT"];
[dateFormatter setTimeZone:gmt];
[dateFormatter setDateFormat:#"MMM dd, yyyy"];
NSString *date_str=[NSString stringWithFormat:#"%#",from_date];
NSLog(#"%#",date_str);
NSString *date_str1=[NSString stringWithFormat:#"%#",to_date];
NSLog(#"%#",date_str1);
NSDate *starting_date = [dateFormatter dateFromString:date_str];
NSDate *end_date = [dateFormatter dateFromString:date_str1];
NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
NSUInteger unitFlags = NSDayCalendarUnit;
NSDateComponents *components = [gregorian components:unitFlags fromDate:starting_date toDate:end_date options:0];
NSInteger days = [components day];
That code giving total no of days.
How can i get this output?
Thanks
Continuing from your code and assuming,
NSString *date_str=[NSString stringWithFormat:#"%#",#"December 21, 2013"];
NSString *date_str1=[NSString stringWithFormat:#"%#",#"December 28, 2013"];
If you need it within the same month, it can be in this way,
NSDateComponents *component1 = [gregorian components:unitFlags fromDate:starting_date];
NSDateComponents *component2 = [gregorian components:unitFlags fromDate:end_date];
for (int i = component1.day; i <= component2.day; i++) {
NSLog(#"%i", i);
}
But if your dates expand between different months, then you have to add checking for month components in the loop.
I will continue on your code, with some dirty code of mine, but it gets the job done if what you provided is your date format:
NSArray *begining_day = [date_str componentsSeparatedByString:#"/"];
NSMutableArray *part_days = [[NSMutableArray alloc] init];
for (int i = 0; i < days; i++) {
[part_days addObject:([begining_day[0] integerValue] + i)];
}
Now part_days will have your days, BUT! You have to handle the end of each month.
I'm 100% sure you'll find better solutions, but I thought I could share the first thing I thought of, you might benefit from it.
You can try below code:
NSArray *array = [[NSArray alloc] initWithObjects:#"1/12/14",#"2/12/14",#"3/12/14",#"4/12/14",#"5/12/14", nil];
for (int i = 0; i < [array count]; i++) {
NSArray *myArray = [[array objectAtIndex:i] componentsSeparatedByString:#"/"];
[dayArray addObject:[myArray objectAtIndex:0]];
}
NSLog(#"%#",dayArray);
You can incrementally add 24 hours to your startDate until you pass your endDate. Using NSDateComponents you can pick out the day. Instead of logging them with NSLog just store them in a string or array.
NSDate *startDate = [NSDate dateWithTimeIntervalSinceReferenceDate:300000000];
NSDate *endDate = [NSDate dateWithTimeIntervalSinceReferenceDate:302000000];
for (NSDate *nextDate = startDate; [nextDate compare:endDate] < 0; nextDate = [nextDate dateByAddingTimeInterval:24*60*60] ) {
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:nextDate];
NSInteger day = [components day];
NSLog(#"day %li", (long)day);
}
I have two date string and I wanted to get the in between dates.
For example,
NSString *startDate = #"25-01-2014";
NSString *endDate = #"02-02-2014";
In between dates will be (26-01-2014, 27-01-2014, 28-01-2014.......)
preferably include startDate and endDate as well. Most of the question I managed to find asked for number of days. But I needed it to be actual date. Is there anyway that I can get the in between dates?
NSString *start = #"2010-09-01";
NSString *end = #"2010-12-05";
NSDateFormatter *f = [[NSDateFormatter alloc] init];
[f setDateFormat:#"yyyy-MM-dd"];
NSDate *startDate = [f dateFromString:start];
NSDate *endDate = [f dateFromString:end];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorianCalendar components:NSDayCalendarUnit
fromDate:startDate
toDate:endDate
options:0];
NSLog(#"Difference in date components: %d", components.day);
I managed to find this which only returns number of days difference.
NSString *start = #"2010-09-01";
NSString *end = #"2010-12-05";
NSDateFormatter *f = [[NSDateFormatter alloc] init];
[f setDateFormat:#"yyyy-MM-dd"];
NSDate *startDate = [f dateFromString:start];
NSDate *endDate = [f dateFromString:end];
NSMutableArray *dates = [#[startDate] mutableCopy];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorianCalendar components:NSDayCalendarUnit
fromDate:startDate
toDate:endDate
options:0];
for (int i = 1; i < components.day; ++i) {
NSDateComponents *newComponents = [NSDateComponents new];
newComponents.day = i;
NSDate *date = [gregorianCalendar dateByAddingComponents:newComponents
toDate:startDate
options:0];
[dates addObject:date];
}
[dates addObject:endDate];
The array dates now contains the list of dates between startDate and endDate, including those, for midnight in the timezone of the device.
Note, that on some timezones this might cause trouble, as the switch from and to Daylight Saving Time might occur at that moment, see WWDC 2011 Video "Session 117 - Performing Calendar Calculations" for further information. One trick is to shift the hour to a save time, i.e. noon, do the calculation and than subtract 12 hours.
Ok, you're most of the way there. You have a date formatter that converts the date strings to NSDates. You have the number of days between the dates. Now you need to loop from the start date for that many days, adding a variable number of days to the start date.
The method you need is dateByAddingComponents:toDate:options:.
Something like this (goes immediately after your code) :
int days = components.day;
NSDateComponents *daysToAdd = [[NSDateComponents alloc] init];
for (int count = 0; count <= days; count++)
{
daysToAdd.day = count;
NSDate *loopDate = [gregorianCalendar dateByAddingComponents: daysToAdd
toDate: startDate
options: 0 ];
NSLog(#"Day %d = %#", count+1, [f stringFromDate: loopDate]);
}
I haven't tested it, but that's the basic idea...
The code above should include both the start and end dates.
If you don't want to include the start date, make the loop start at count = 1 instead of count = 0.
If you don't want to include the end date, make the loop check count < days.
A little late but found a fix to the 'TIMEZONE' time issue that vikingosegundo talked about in his answer. I simply converted the NSDate to an NSString by calling a stringFromDate method on the formatter *f in your for loop...
for (int i = iStart; i < components.day; ++i) {
NSDateComponents *newComponents = [NSDateComponents new];
newComponents.day = i;
newComponents.hour = 0;
newComponents.minute = 0;
newComponents.second = 0;
NSDate *date = [gregorianCalendar dateByAddingComponents:newComponents
toDate:startDate
options:0];
// THIS IS THE CODE I ADDED TO MINE //
// convert NSDate to string calling on *f (NSDateformatter)
NSString *string = [f stringFromDate:date];
// split the string to separate year, month, etc...
NSArray *array = [string componentsSeparatedByString:#"-"];
// create second NSString withFormat and only add the variable from the date that you find pertinent
NSString *sDateNew = [NSString stringWithFormat:#"%#-%#-%#",array[0],array[1],array[2]];
// then simply add the sDateNew string to dates array
[dates addObject:sDateNew];
}
I think this should be put into the comment section of your answer vikingsegundo but it would not let me.
I cannot use a UIDatePicker. I just want to throw that out at the very beginning before all the commenters tell me to just use a UIDatePicker. I want to have a Picker Wheel that shows all the day of the year, leading up to today, and display it as Day: 1/Jan 1, Day: 2/Jan 2 and so on. Here is what I have so far, which detects what day 'number' of the year it is, and populates the PickerWheel with all the dates leading up to today:
NSCalendar *currentCalendar = [NSCalendar currentCalendar];
NSDate *today = [NSDate date];
NSInteger dc = [currentCalendar ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSYearCalendarUnit
forDate:today];
options = [[NSMutableArray alloc]init];
for (int index = 1; index <= dc; index++)
{
NSString *pickerItemTitle = [NSString stringWithFormat: #"Day: %d", index];
[options addObject: pickerItemTitle];
}
What can I do to make it also match up the NSInteger with the date, and have that be part of the pickerItemTitle as well?
Got it figured out. Added some code to form a date based off integer of day into the loop. Now, the viewWillAppear method that sets the array for the uipickerview looks like this:
- (void)viewWillAppear:(BOOL)animated
{
NSCalendar *currentCalendar = [NSCalendar currentCalendar];
NSDate *today = [NSDate date];
NSInteger dc = [currentCalendar ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSYearCalendarUnit
forDate:today];
options = [[NSMutableArray alloc]init];
for (int index = 1; index <= dc; index++)
{
NSDateComponents *components = [[NSDateComponents alloc] init];
[components setDay:index];
NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [gregorian dateFromComponents:components];
NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
[formatter setDateFormat:#"MMM dd"];
NSString *articleDateString = [formatter stringFromDate:date];
NSString *pickerItemTitle = [NSString stringWithFormat: #"Day: %d/%#", index, articleDateString];
[options addObject: pickerItemTitle];
}
[super viewWillAppear:YES];
}