Question

What will the return value for performSelector: if I pass a selector that returns a primitive type (on object), such as ‘week’ on NSDateComponents (which will return an int)?

Answer 1

An example of using NSInvocation to return a float:

SEL selector = NSSelectorFromString(@"someSelector");
if ([someInstance respondsToSelector:selector]) {
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:
                                [[someInstance class] instanceMethodSignatureForSelector:selector]];
    [invocation setSelector:selector];
    [invocation setTarget:someInstance];
    [invocation invoke];
    float returnValue;
    [invocation getReturnValue:&returnValue];
    NSLog(@"Returned %f", returnValue);
}