objective c dynamic object creation

Question

Quick question for you. I want to be able to create an instance of an object. The object type is based of a string.

In php you can just replace the class name with a string, but I doubt it is that easy in Objective c.

NSString * className;
id theObject;
className = @"TestObject";
theObject = [[className alloc] init];

here is a break down of what it might look like. I want to try and avoid using a giant case style statement.

Is it possible to use the selector system for this?

any ideas?

Cheers

Alex Rozanski · Accepted Answer · 2010-02-01 09:29:08Z

30

You can get a Class object dynamically with NSClassFromString()

Class c = NSClassFromString(@"ClassName");
id obj = [[c alloc] init];

edited Feb 1, 2010 at 9:29

Alex Rozanski

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answered Feb 1, 2010 at 9:08

Jesús A. Álvarez

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1 Comment

Dark Templer Over a year ago

Without a doubt this community is the best. Thank you. That worked like a charm

Vladimir · Accepted Answer · 2010-02-01 09:15:57Z

6

You can get a class by its name using one of the following obj-c runtime functions (you may need to import header:

id objc_lookUpClass(const char *name)
id objc_getClass(const char *name)

So your code may look like (have not tested it though):

NSString * className = @"TestObject";
id theObject = nil;
Class myClass = objc_lookUpClass([className UTF8String]);
if (myClass)
   theObject = [[myClass alloc] init];

answered Feb 1, 2010 at 9:15

Vladimir

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