if statements and table views problem

[pete42]

Hi, I have been having with implementing a function in a table view sports app. my app is a schedule and im trying implement a today navbar button. this button will go to the cell of the game when it is the right date. I believe that the way i am getting the date is good

self.dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[self.dateFormatter setDateStyle:NSDateFormatterShortStyle];
[self.dateFormatter setTimeStyle:NSDateFormatterNoStyle];

//gameDay is a NSString
gameDay= [self.dateFormatter stringFromDate:[NSDate date]];

but when i go to do some if statements only the first one works when i use one equal sign

int row;	
	
if (gameDay = @"09-01-10") {
	row = 46;
	[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
	}
	
	else if (gameDay = @"14-01-10") {
		row = 47;
		[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
	}

and when i use two equal signs

int row;	
	
	if (gameDay == @"09-01-10") {
		row = 46;
		[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
	}
	
	else if (gameDay == @"14-01-10") {
		row = 47;
		[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
	}

nothing happens even though i know that two equal should be right.

I want to know why it only works for the first one with one equal but not for the one, in my opinion is right, with 2 equals.

A solution for this problem would be really great because i have trying to do two functions like this and they dont work.

thanks

[BrianSlick]

if ([aString isEqualToString: anotherString])

[_sjc_]

In your example code, gameDay and @"09-01-10" are both examples of NSString objects. In order to compare them, you need to use one of their comparison functions. eg.

if( [gameDay isEqualToString: @"09-01-10"] ) { ... }

Basically, this is sending one string the -isEqualToString: message, along with another string to compare it to. This returns YES or NO, depending on whether they're equal.

(You could also do [@"09-01-10" isEqualToString: gameDay] ... it's the same difference.)

'=' is the assignment operator. In your first example, you're assigning the address of the object @"09-01-10" to the variable gameDay. (Since this was non-zero, this also evaluated to the same as YES, which is why the code was run.)

'==' is the comparison operator, but it only works on C primitives. In this case, you were comparing the ADDRESSES where the two strings were held in memory, which were different, which is why it was failing.

EDIT: Sorry, BrianSlick, you answered while I was still typing

[pete42]

that seems like it would work but it just crashes the app every time. this is the whole code im using:

-(void) today:(id)sender {
	
	int row;	

	if ([gameDay isEqualToString:@"10-01-09"]) {
		row = 46;
		[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
	}
	
	else if ([gameDay isEqualToString: @"10-01-14"]) {
		row = 47;
		[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
	}
	
	 
	else {
	 
	 UIAlertView *myAlert2 = [[UIAlertView alloc] initWithTitle:@"No Game Today" message:@"The Next Game is on\nJanuary 14, 2010" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
	 [myAlert2 show];
	 [myAlert2 release];
	 
}
}

I always get "EXC_BAD_ACCESS"

[_sjc_]

Are you retaining gameDay? stringFromDate: returns an autoreleased string object, which means that by the time you come to compare against it, it will probably have been disposed of. Try:

gameDay= [[self.dateFormatter stringFromDate:[NSDate date]] retain];

[pete42]

thanks you so much its working.

[BrianSlick]

Better yet, use @properties.