如何查找存储在2个字符串中的日期之间的天数

Question

我有两个字符串都采用以下日期格式（2011-03-22）。
我必须比较它们并找出它们之间的天数。

谁能告诉我如何做到这一点..

还请告诉我将它们转换回 NSDate 的正确方法。

Answer 1

我刚刚输入的内容可能有几个错误，但它本身就说明了问题，您应该明白了。

NSString *dateStringA = @"2011-03-22";

NSString *dateStringB = @"2011-03-27";

NSDateFormatter *df = [[[NSDateFormatter alloc] init] autorelease];
df.dateFormat = @"yyyy-MM-dd";

NSDate *dateA = [df dateFromString:dateStringA];
NSDate *dateB = [df dateFromString:dateStringB];

NSDateComponents *comps = [[NSCalendar currentCalendar] components:NSDayCalendarUnit fromDate:dateA toDate:dateB options:0];
int daysBetweenDates = comps.day; //This is your days between the 2 dates


NSDate *intervalDate = [[NSCalendar currentCalendar] dateFromComponents:comps]; //This date object represents the duration between them

Answer 2

对于字符串到日期

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyy-MM-dd HH:mm:ss ZZZ"];
NSDate *dateFromString = [[NSDate alloc] init];
dateFromString = [dateFormatter dateFromString:<NSString containing date>];

对于日期到字符串

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