增加NSDate +1天方法Objective-C？ [英] Increase NSDate +1 day method Objective-C?

问题描述

这是我的方法，我使用在我的导航栏增加一天，并将日的名称设置为标题。我知道这是错误的，因为我设置今天变量每次它的调用。但是我不知道如何在每次调用此方法时增加+1天。

This is my method I use for increasing by one day in my navigationBar, and setting the name of the day as a title. I know it's wrong because I set "today" variable every time its called. But I can't figure out how to increase +1 day every time I call this method.

-(void)stepToNextDay:(id)sender
{
    today = [NSDate date];
    NSDate *datePlusOneDay = [today dateByAddibgTimeInterval:(60 * 60 * 24)];
    NSDateFormatter *dateformatterBehaviour = [[[NSDateFormatter alloc]init]autorelease];
    [dateFormatter setDateFormat:@"EEEE"];
    NSString *dateString = [dateFormatter stringFromDate:datePlusOneDay];
    self.navigationItem.title = datestring;
}

推荐答案

在您的视图控制器的属性（ivar，...）。

Store the date your are showing in a property (ivar, ...) of your view controller. That way you can retrieve the current setting when you go to the next day.

如果要可靠地添加日期，请使用NSCalendar和NSDateComponents获取1天

If you want to reliably add dates, use NSCalendar and NSDateComponents to get a "1 day" unit, and add that to the current date.

NSCalendar*       calendar = [[[NSCalendar alloc] initWithCalendarIdentifier: NSGregorianCalendar] autorelease];
NSDateComponents* components = [[[NSDateComponents alloc] init] autorelease];
components.day = 1;
NSDate* newDate = [calendar dateByAddingComponents: components toDate: self.date options: 0];

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