Object named string

if i create a class object i do:

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


but how can I call this name in a string? (I am asking this question because I have to do it in a loop and the object name is dynamic)

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




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3 answers

If you want to pass an object by string name, you store your objects in an 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 a variable name from a string. What are you trying to achieve here? You can use a dictionary to look up a variable from a string key.

Check this question



the need to change the variable name ( Item *???

) is very unusual - there is often a preprocessor abuse.

instead, I think you can search for instances of types by name.

To do this, use a combination id

, Class

apis, NSClassFromString



is a pointer to an undefined object objc that the compiler will "accept" any declared message:

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


now you can query aString

for execution selectors that it cannot respond to. it is like a void*

for objc. note that you will get a runtime exception if you pass a variable id

using a selector it doesn't respond to.

next, type Class


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


to put it all together to instantiate 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];




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