object with the name of a string

if I create an object of a class, I do:

Item *item01 = [[Item alloc] init];

but how do I give it a name I have in a string? (I make this question because I have to do this in a 开发者_开发百科loop, and the name of object is dynamic)

NSString *aString = [NSString stringWithFormat:@"%@", var];
Item *??? = [[Item alloc] init];

thanks!

If you want to refer the object by the name of the string, you would store your objects in NSMutableDictionary and set the key to the name.

For example:

// Someplace in your controller create and initialize the dictionary
NSMutableDictionary *myItems = [[NSMutableDictionary alloc] initWithCapacity:40];

// Now when you create your items
Item *temp = [[Item alloc] init];
[myItems setObject:temp forKey:@"item01"];
[temp release];

// This way when you want the object, you just get it from the dictionary
Item *current = [myItems objectForKey:@"item01"];

You cannot have variable name from a string. What are you trying to achieve here? You can use dictionary for looking up variable from a string key.

Check this similar question

the need to change the name of a variable (Item *???) is very unusual -- it's often preprocessor abuse.

instead, i think you may be looking to create instances of types by name.

to do this use a combination of id, Class apis, NSClassFromString.

id is a pointer to an undefined objc object, which the compiler will 'accept' any declared message to:

id aString = [NSString stringWithFormat:@"%@", var];

now you can request aString to perform selectors it may not respond to. it's similar to a void* for an objc type. note that you'll get a runtime exception if you message an id variable using a selector it does not respond to.

next, the Class type:

Class stringClass = [NSString class];
NSString * aString = [stringClass stringWithFormat:@"%@", var];

to combine all this to create an instance of a type by name:

NSString * className = [stringClass stringWithFormat:@"%@", var];
Class classType = NSClassFromString(className);
assert(classType && "there is no class with this name");
id arg = [[classType alloc] init];