[Objective-C] 日付を比較する

指定した期間内にアクセスすると1度だけダイアログを出すプログラムを作ってみた

こんな感じで

EventDateRecorder.h
#import <Foundation/Foundation.h>
@interface EventDateRecorder : NSObject
+ (BOOL)christmasEventDateRecorder;
@end

EventDateRecorder.m
#import "EventDateRecorder.h"

// ダイアログ表示期間
static NSString *const chrismasEventDateKey = @"chrismasEventDate";
static NSString *const chrismasfromDateString = @"2015-12-25 00:00:00";
static NSString *const chrismasAfterDateString = @"2015-12-26 00:00:00";

@implementation EventDateRecorder

+ (BOOL)chrismasEventDateRecorder
{
   BOOL isChrismasEvent = [self eventDateRecorderWithKey:chrismasEventDateKey fromDateString:chrismasfromDateString afterDateString:chrismasAfterDateString];
    return isChrismasEvent;
}

+ (BOOL)eventDateRecorderWithKey:(NSString *)eventKey fromDateString:(NSString *)fromDateString afterDateString:(NSString *)afterDateString
{
    NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    [formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];

    NSDate *fromDate = [formatter dateFromString:fromDateString];
    NSDate *afterDate = [formatter dateFromString:afterDateString];

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSDate *eventDate = [defaults objectForKey:eventKey];
    NSDate *now = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone systemTimeZone] secondsFromGMT]];
    if ([now compare:fromDate] == NSOrderedDescending && [now compare:afterDate] == NSOrderedAscending) {
        if (eventDate) {
            if([eventDate compare:fromDate] == NSOrderedDescending && [eventDate compare:afterDate] == NSOrderedAscending) {
                return NO;
            } else {
                [defaults setObject:now forKey:eventKey];
                [defaults synchronize];
                return YES;
            }
        } else {
            [defaults setObject:now forKey:eventKey];
            [defaults synchronize];
            return YES;
        }
    } else {
        return NO;
    }
}
@end

使い方は

BOOL isChrismasEvent = [EventDateRecorder chrismasEventDateRecorder];
if (isChrismasEvent) {
//YESが返ってきた時の処理;
} else {
}