如何判断从现在到 NSDate 的天数? [英] How to tell the amount of days from now until an NSDate?

问题描述

如何知道从现在到我的应用中指定的日期的天数?这是我到目前为止所拥有的，但每次都会出现-30"，无论日期是什么:

How can I tell the amount of days from now until the date specified in my app? Here is what I have so far, but it comes up with "-30" every time, no matter what the date is:

NSDate * selected = [DatePicker date];
NSString * date = [selected description];

NSDateComponents *components = [[NSCalendar currentCalendar] components:NSDayCalendarUnit 
                                                              fromDate:DatePicker.date];

CalLabel1.text = [NSString stringWithFormat:@"%d", [components day]];

NSDateFormatter *temp = [[NSDateFormatter alloc] init];
[temp setDateFormat:@"dd/MM/yyyy"];
NSDate *stDt = [temp dateFromString:[temp stringFromDate:[NSDate date]]];
NSDate *endDt =  [temp dateFromString:[temp stringFromDate:[NSString stringWithFormat:@"%d", [components date]]]];
unsigned int unitFlags = NSMonthCalendarUnit | NSDayCalendarUnit;
NSCalendar *gregorian = [[NSCalendar alloc]
                         initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components:unitFlags fromDate:stDt  toDate:endDt  options:0];
int days = [comps day];

NSLog(@"%i", [comps day]);

推荐答案

NSDate * selected = [DatePicker date];
NSCalendar *gregorian = [[NSCalendar alloc] 
                          initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components: NSDayCalendarUnit 
                                       fromDate: [NSDate date]  
                                         toDate: selected  
                                        options: 0];
int days = [comps day];

NSLog(@"%i", [comps day]);

这会计算从现在到所选日期之间的天数.您对日期格式化程序的所有弄乱都是错误的，而且没有必要.

This calculates the number of days between now and the selected date. All your messing around with the date formatter was wrong and not necessary.

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