nsdateformatter - 如何使用日期格式化程序并比较两个日期字符串

Question

大家好，我想比较两个日期并执行一些操作我被困在洞天试图尽我所能，但我知道我可能遗漏了一些东西或做错了什么，任何帮助将不胜感激。在我的代码下面

-(void)dailyCalendarViewDidSelect:(NSDate *)date
{
    //You can do any logic after the view select the date
    NSDateFormatter *dateformat = [[NSDateFormatter alloc] init];
    [dateformat setDateStyle:NSDateFormatterMediumStyle];
    [dateformat setDateStyle:NSDateFormatterMediumStyle] ;
    
   datestring1= [dateformat stringFromDate:date]; // date value by current selected date from my cal view
   NSLog(@"%@",datestring1);//output May 5, 2015
 // NSLog(@"%@",date);//output 2015-05-05 15:56:32 +0000
    datestring2 = [dateformat stringFromDate:mydate];//already fetched value
    NSLog(@"%@",datestring2);// output May 5, 2015
  // NSLog(@"%@",mydate);// output 2015-05-05 08:47:16 +0000
    if (datestring1 == datestring2) {
        
        NSLog(@"good to go");//not able to get this value
        
        
    }
    
    /*//even i try this block too
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init];
    [dateFormat setDateFormat:@"yyyy-MM-dd"];
    mydate1 = [[NSDate alloc]init];
    mydate1 = [dateFormat dateFromString:datestring1];
    NSLog(@"%@",mydate1);//otpt null
    mydate2 = [[NSDate alloc]init];
    mydate2 = [dateFormat dateFromString:datestring2];
    NSLog(@"%@",mydate2);//otpt //null
   
    if (mydate1 == mydate2) {
        
        NSLog(@"good to go");//getting value without matching condition
      

    }
      */
    
    
   
}

请看一下任何帮助都会有所帮助提前谢谢

Answer 1

对于比较两个日期，两个日期必须是相同的格式

if ([date1 compare:date2] == NSOrderedDescending) 
{
    NSLog(@"date1 is later than date2(greater than current date)");
} 
else if ([date1 compare:date2] == NSOrderedAscending)
{
    NSLog(@"date1 is earlier than date2 (less than current date)");    
} 
else 
{
    NSLog(@"dates are the same");  
}

或者试试这个

if ([[date1 earlierDate:date2] isEqualToDate:date1])
{
    NSLog(@"date1 is earlier than date2 (less than current date)");
}
else if ([[date1 laterDate:date2] isEqualToDate:date1])
{
    NSLog(@"date1 is later than date2(greater than current date)");
}
else 
{
    NSLog(@"dates are the same");  
}