Comparing two dates for daily reward in iOS game - iphone

Question

I was implementing a 'daily reward' method in order to give some coins every day in my game.
I have a json that contains the actual date and time.
The issue is that I don't know how to compare the dates.
Here is my code -
#implementation ItemRewardManager
+(NSDate *)dateFromUTCTimeStamp:(NSString *)dateString{
NSDateFormatter *df = [[NSDateFormatter alloc] init];
df.dateFormat = #"yyyy-MM-dd HH:mm:ss";
NSDate *myDate = [df dateFromString: dateString];
NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:#"GMT"];
[df setTimeZone:gmt];
[[NSUserDefaults standardUserDefaults] setObject:myDate forKey:#"lastDatePlayed"];
[[NSUserDefaults standardUserDefaults] synchronize];
}
-(void)getData
{
NSData *jsonData = [NSData dataWithContentsOfURL:[NSURL URLWithString:dateUrl]];
id jsonObjects = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil];
NSArray *keys = [jsonObjects allKeys];
// values in foreach loop
for (NSString *key in keys) {
NSLog(#"%# is %#",key, [jsonObjects objectForKey:key]);
}
}
+(void)dailyReward{
NSLog(#"llega al daily");
NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init];
[dateFormat setDateFormat:#"HH:mm:ss zzz"];
NSDate *now = [NSDate date];
NSString *dateString = [dateFormat stringFromDate:now];
if([[[NSUserDefaults standardUserDefaults] objectForKey:#"lastDatePlayed"] isEqualToString: dateString])
{
NSLog(#"Actual date is the same as json date");
UIAlertView* alert = [[[UIAlertView alloc] initWithTitle:nil
message:#"You have win 5 coins! Come back tomorrow for more."
delegate:nil
cancelButtonTitle:#"Ok"
otherButtonTitles: nil] autorelease];
[alert show];
return;
}
}
#end
So, when I open my app and call this method, my app crashes for some reasone.
I think the problem might be on the comparison of the two dates.
Can someone tell me if there is something wrong?

Answer 1

Use following.
if ([date1 compare:date2]==NSOrderedSame)
date1 and date2 are NSdate objects.

Answer 2

NSDate has methods for comparing dates.
Here they are:
isEqualToDate: Returns a Boolean value that indicates whether a given
object is an NSDate object and exactly equal the receiver.
- (BOOL)isEqualToDate:(NSDate *)anotherDate
laterDate: Returns the later of the receiver and another given date.
- (NSDate *)laterDate:(NSDate *)anotherDate
earlierDate: Returns the earlier of the receiver and another given
date.
- (NSDate *)earlierDate:(NSDate *)anotherDate

Answer 3

Try like this. It may help you
NSDate *now = [NSDate date]; // current date
NSDate *newDate = [dateFormat dateFromString:[[NSUserDefaults standardUserDefaults] objectForKey:#"lastDatePlayed"]]; // server date
NSComparisonResult result;
result = [now compare:newDate]; // comparing two dates
if(result == NSOrderedAscending)
NSLog(#"now is less");
else if(result == NSOrderedDescending)
NSLog(#"newDate is less");
else
NSLog(#"Both dates are same");

Answer 4

Use this code.
NSDate *date = [NSDate date];
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
[dateFormatter1 setDateFormat:#"MM/dd/yyyy"];
NSDate *ServerDate = [dateFormatter1 dateFromString:#"03/01/2013"];
[dateFormatter1 release];
NSTimeInterval interval = [date timeIntervalSinceDate:ServerDate];
int diff=interval/1440;
This is implemented code.