Cast object in a call with performSelectorOnMainThread iOS

Question

If I use

[self performSelectorOnMainThread:@selector(uploadDidEnd:) withObject:foo
        waitUntilDone:YES]

In the method -(void)uploadDidEnd:(id)sender

Which object is sender? in the call foo is a custom class? How can I convert this sender in my object?

I'm trying to cast but I'm having

'-[_NSThreadPerformInfo CountY]: unrecognized selector sent to instance 0x52bbd0'

In notifications, I use a cast from sender to NSNotification and notification have the object property, but for NSThread I didn't found.

Thanks.

Answer 1

You can think of:

[self performSelectorOnMainThread:@selector(uploadDidEnd:)
      withObject:foo
      waitUntilDone:YES]

as sort of the same as:

[self uploadDidEnd:foo];

Are you sure that's what you're trying to do?

If so: inside your uploadDidEnd: implementation, you can cast foo to whatever object type it really is like so:

- (void)uploadDidEnd:(id)sender
{
  FooClass *foo = (FooClass *)sender;
  [foo doSomething]; // or whatever
}

Answer 2

1. The argument declared a sender is the only parameter passed to your method. performSelectorOnMainThread:withObject:waitUntilDone: passes its argument after withObject to the selector to be performed, so yes, here foo will be passed to uploadDidEnd:

2. Casting is not a solution. Objective-C is a dynamic language, so even if casting eliminates compiler warnings, the actual implementation of the object wouldn't change, so it naturally would not repond to messages.