Question

I have a class which converts multiple date formats.

It works when I do this:

-(NSString*)getTimeStampWithFormat:(NSString*) formatStr{
    dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:formatStr];
    NSString *currentDate = [dateFormatter stringFromDate:[NSDate date]];
    return currentDate;
}

it does not work when I do this

-(void) initDF{
    dateFormatter = [[NSDateFormatter alloc] init];
}

-(NSString*)getTimeStampWithFormat:(NSString*) formatStr{
    [dateFormatter setDateFormat:formatStr];
    NSString *date = [dateFormatter stringFromDate:[NSDate date]];
        return currentDate;
}

I am calling the getTimeStampWithFormat: method multiple times to convert different formats. In the second approach, I am allocating memory only once and converting multiple times it gives nil.

Any help would be appreciated, thanks.

Answer 1

As apple said:

Creating a date formatter is not a cheap operation. If you are likely to use a formatter frequently, it is typically more efficient to cache a single instance than to create and dispose of multiple instances. One approach is to use a static variable.

But I am wondering why it always return nil, could you please show us some of the format strings?

Note: Any body know how to add comment to the question? I cannot find the ‘comment’ button.