Objective-C performSelector does not call a method with parameter

Question

Hi all,

I'm having a problem with performSelector. It works if I call a method without parameters, but it doesn't even call the method if I pass a parameter.

Example:

- (void)test
{
 NSLog(@"test"); //it works!!
}    
...
[self performSelector:@selector(test) withObject:nil afterDelay:1.0];


- (void)switchOn:(NSNumber *) index
{
 NSLog(@"switchOn"); //it doesn't work :-(
}   
....
NSLog(@"int is %d", [((NSNumber *)obj) intValue]); //print the correct value
[self performSelector:@selector(switchOn:) withObject:obj afterDelay:1.0];

I get no errors neither. Where could it be the problem?

thanks

Answer 1

What is the type of the parameter for the switchOn: selector?

It must be of type id otherwise performSelector:WithObject: won't work. To quote the docs:

aSelector should identify a method that takes a single argument of type id. For methods with other argument types and return values, use NSInvocation.

Answer 2

performSelectorWithObject: sends a message to the selector with the object you supplied as the first argument. The receiving method must accept a single parameter of type id. For anything else use NSInvocation.

You might want to check out a similar question about this.

Answer 3

Try to use:

- (void)switchOn:(id)index