Date 中的字符串不起作用

Question

    -(void)viewLogAction
   {
NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
[formatter setDateFormat:@"yyyy-MM-dd"];
NSDate *date = [formatter dateFromString:_selectedDate];
formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd-MM-yyyy"];

NSString *convertedString = [formatter stringFromDate:date];

 _allFood = [CoreDataMethods foodLogFromCoreData:convertedString];
if([_allFood count]==0)
{
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"No data" message:@"Sorry, No food item to display on this date" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];

}
else{

[self performSegueWithIdentifier:@"viewLogSegue" sender:self];

}
}

这是我的代码。 NSString _selectedDate 具有值 2017-05-09，但行 NSDate *date = [formatter dateFromString:_selectedDate]; 未将任何值传递给 date。请帮我找出问题所在。

Answer 1

试试这个

NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
[formatter setDateFormat:@"yyyy-MM-dd"];
NSDate *date = [formatter dateFromString:_selectedDate];
[formatter setDateFormat:@"dd-MM-yyyy"];

Answer 2

您发布的代码很好，如果 _selectedDate 不为零，则可以正常工作。检查您是否正确设置了 _selectedDate 中的值。

Date 中的字符串不起作用

String from Date not working

xcode

objective-c

nsdate

nsdateformatter

ios