Dynamically invoke a class method in Objective C

by

Instead of:

[someOtherObject invokeSelector:@selector(someMethod) forClass:[SomeClass class];

call:

[[SomeClass class] performSelector:@selector(someMethod)];

Example (using GNUstep …)

file A.h

#import <Foundation/Foundation.h>
@interface A : NSObject {}

- (NSString *)description;
+ (NSString *)action;
@end

file A.m

#import <Foundation/Foundation.h>
#import "A.h"

@implementation A

- (NSString *)description
{
    return [NSString stringWithString: @"A"];
}

+ (NSString *)action
{
    return [NSString stringWithString:@"A::action"];
}

@end

Somewhere else:

A *a = [[A class] performSelector:@selector(action)];
NSLog(@"%@",a);

Output:

2009-11-22 23:32:41.974 abc[3200] A::action

nice explanation from http://www.cocoabuilder.com/archive/cocoa/197631-how-do-classes-respond-to-performselector.html:

“In Objective-C, a class object gets all the instance methods of the
root class for its hierarchy. This means that every class object
that descends from NSObject gets all of NSObject’s instance methods –
including performSelector:.”

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