Question

I have an Objective-C++ program that uses an NSSearchField. Specifically, the NSSearchField is wrapped in a QMacCocoaViewContainer derivative (Qt). How can I set things up so that I can receive notification of textDidEndEditing from a Qt signal? Will I need a pure Objective-C class that uses NSNotificationCenter?

Answer 1

If you’re on iOS4, looks like you can have your notification delivered to a block instead. NSNotificationCenter sports this method:

- (id)addObserverForName:(NSString *)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *))block NS_AVAILABLE(10_6, 4_0);

Then you could do something like:

MyClass.m:

static void (^receiveNote)(NSNotification *) = ^(NSNotification * note)
{
    UITextField * field = [ note object ] ;
    // forward notification to C++ here
} ;

…

@implementation MyClass

…

-(void)setUpNotifications
{
    [ [ NSNotificationCenter defaultCenter ] addObserverForName:UITextFieldTextDidChangeNotification 
                                                         object:self.textField 
                                                          queue:[ NSOperationQueue mainQueue ] 
                                                     usingBlock:receiveNote ] ;
}