Getting values from an array of wrapped structs using NSValue

[martin]

Hi guys!

I am trying to get back a value that I put in an array of structs wrapping these structs using NSValue.

I have these on my myAppDelegate.h :

typedef struct {
	NSInteger	ticketId;
	NSString	*eventTitle;
	NSString	*eventInfo;
} TicketDataStruct;

@interface myAppDelegate : NSObject <UIApplicationDelegate> {
	[...]
	NSMutableArray *dataArray;
	[...]
}
[...]
@property (nonatomic, retain) NSMutableArray *dataArray;
[...]

then, in myAppDelegate.m:

@synthesize dataArray;

#pragma mark -
#pragma mark Application lifecycle

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
	
	TicketDataStruct str;
	str.ticketId = 543;
	str.eventTitle = @"My event";
	str.eventInfo = @"My event info";
	
	NSValue *myValue = [NSValue value:&str withObjCType:@encode(TicketDataStruct)];
	
	dataArray = [[NSMutableArray alloc] initWithObjects:nil];
	[dataArray addObject:miValor];
	[...]
}

Now, How can I get access to the values of the structs?
I am trying with this, but I am getting nil (This code is inside (UITableViewCell *)tableViewUITableView *)tableView cellForRowAtIndexPathNSIndexPath *)indexPath):

	[...]
	myAppDelegate *delegate = [[UIApplication sharedApplication] delegate];
	TicketDataStruct retVal;
	NSValue *t = [[NSValue alloc] initWithBytes:[delegate.dataArray objectAtIndex:indexPath.row] objCType:@encode(TicketDataStruct)];
	[t getValue:&retVal];
	topLabel.text = [[NSString alloc] initWithString:retVal.eventTitle];
	[...]

But it doesn't work. I am getting nil in retVal.eventTitle.

Can you help me?
Thanks!

[martin]

Ok, to make it easier...
I need to get back values from a struct wrapped inside a NSValue.
Any ideas?

Thank you

[dmf1978]

Forget about structs. That is plain wrong!!
Instead, write classes. Then, create objects based on the class and add these to the NSMutableArray.
Now, you can access to the members like this:

MyClass *myObject = [[MyClass alloc] init];
myObject = [delegate.dataArray objectAtIndex:indexPath.row];
topLabel.text = myObject.eventName;

[Duncan C]

Originally Posted by dmf1978

Forget about structs. That is plain wrong!!
Instead, write classes. Then, create objects based on the class and add these to the NSMutableArray.
Now, you can access to the members like this:

MyClass *myObject = [[MyClass alloc] init];
myObject = [delegate.dataArray objectAtIndex:indexPath.row];
topLabel.text = myObject.eventName;

It's not wrong. It's old school, and not very OOP, but it should work, and sometimes this approach ends up being the right solution, even if it isn't very elegant or flexible. Life is full of trade-offs and compromises...


To the OP, I didn't see anything obvious wrong with your code. Then again, it's almost 10:00 pm here, and I had a beer with dinner. My mental focus is getting a little soft...

[sanniv]

Originally Posted by dmf1978

Forget about structs. That is plain wrong!!
Instead, write classes. Then, create objects based on the class and add these to the NSMutableArray.
Now, you can access to the members like this:

MyClass *myObject = [[MyClass alloc] init];
myObject = [delegate.dataArray objectAtIndex:indexPath.row];
topLabel.text = myObject.eventName;

Just use this:
MyClass *myObject = [delegate.dataArray objectAtIndex:indexPath.row];
topLabel.text = myObject.eventName;

other wise you will lead to memory leak....