Discussion

If the selector is already implemented on the receiver, the existing implementation will be invoked before the signal fires.

If the selector is not yet implemented on the receiver, the injected implementation will have a void return type and accept only object arguments. Invoking the added implementation with non-object values, or expecting a return value, will result in undefined behavior.

This is useful for changing an event or delegate callback into a signal. For example, on an NSView:

 [[view rac_signalForSelector:@selector(mouseDown:)] subscribeNext:^(RACTuple *args) {
     NSEvent *event = args.first;
     NSLog(@"mouse button pressed: %@", event);
 }];

selector - The selector for whose invocations are to be observed. If it doesn’t exist, it will be implemented to accept object arguments and return void. This cannot have C arrays or unions as arguments or C arrays, unions, structs, complex or vector types as return type.

Returns a signal which will send a tuple of arguments upon each invocation of the selector, then completes when the receiver is deallocated. next events will be sent synchronously from the thread that invoked the method. If a runtime call fails, the signal will send an error in the RACSelectorSignalErrorDomain.

Discussion

If the selector is not yet implemented and has a return value, the injected method will return all zero bits (equal to nil, NULL, 0, 0.0f, etc.).

selector - The selector for whose invocations are to be observed. If it doesn’t exist, it will be implemented using information from protocol, and may accept non-object arguments and return a value. This cannot have C arrays or unions as arguments or return type. protocol - The protocol in which selector is declared. This will be used for type information if the selector is not already implemented on the receiver. This must not be NULL, and selector must exist in this protocol.

Returns a signal which will send a tuple of arguments on each invocation of the selector, or an error in RACSelectorSignalErrorDomain if a runtime call fails.