iOS Quick hand with array of strings

[teengohan]

I have the following code in my viewDidLoad meathod:

	for (id key in dictionary) {
		NSString *name;
		name = [dictionary valueForKey:@"name"];
		[listOfNames addObject:name];
		NSLog(name);

	}

list of names is declared in the header file as:

	@interface RootViewController : UITableViewController {
	NSMutableArray *listOfNames;
}
@property (nonatomic, retain) NSMutableArray *listOfNames;
 

@end

For some reason the console output is what I expected, a list of names but no values are being added to the array. I put a breakpoint in at the end of viewDidLoad and the array has zero entries. Does anyone know where i am going wrong here?

 

[robbieduncan]

Where are you creating listOfNames? Declaring a property is declaring a variable: a space to store the object in. It does not create a NSMutableArray object for you. You must create the object somewhere and assign that to the property.

 

[teengohan]

Looks like I was misunderstanding a bit of objective c there. I thought it was initialised when I first assigned it values here:

[listOfNames addObject:name];

is my problem that I have declared the array but not initialised it? If so how do I initialise it? Sorry for newbie question, I'm new to this

 

[Scott90]

Looks like I was misunderstanding a bit of objective c there. I thought it was initialised when I first assigned it values here:

[listOfNames addObject:name];

is my problem that I have declared the array but not initialised it? If so how do I initialise it? Sorry for newbie question, I'm new to this

NSMutableArray *listOfNames = [[NSMutableArray alloc] initWithCapacity:[dictionary count]]

If you put this right before your for loop, it should work. You now have initialized (initWithCapacity) the variable so you can add objects to it.

 

[teengohan]

Ok, I did that but now I get a yellow warning that the "Local declaration of 'listOfNames' hides instance variable". I ned to be able to access this array after this meathod is done as I need to use its contents in another part of my app, one example is I later use this array to populate a table..

 

[Scott90]

Ok, I did that but now I get a yellow warning that the "Local declaration of 'listOfNames' hides instance variable". I ned to be able to access this array after this meathod is done as I need to use its contents in another part of my app, one example is I later use this array to populate a table..

I'm sorry, forgot it was an ivar. The correct code is:

listOfNames = [[NSMutableArray alloc] initWithCapacity:[dictionary count]];

 

[teengohan]

Excelent that did the trick, thanks for the help.

 

[dejo]

	for (id key in [COLOR="Red"][B]dictionary[/B][/COLOR]) {
		...

Are you really wanting to do enumeration on a dictionary, a mechanism that's meant for arrays?

 

[robbieduncan]

Are you really wanting to do enumeration on a dictionary, a mechanism that's meant for arrays?

He probably wanted to do this:

for (id key in [dictionary keyEnumerator])

Which is apparently legal