Subclass NSUserNotificationCenter

// clang test.m -framework Foundation

#import <Foundation/Foundation.h>

@interface TestNotificationCenter : NSUserNotificationCenter
- (instancetype)init;
@end

@implementation TestNotificationCenter

- (instancetype)init {
  if ((self = [super init])) {
  }
  return self;
}

- (BOOL)isKindOfClass:(Class)cls {
  if ([cls isEqual:NSClassFromString(@"_NSConcreteUserNotificationCenter")]) {
    return YES;
  }
  return [super isKindOfClass:cls];
}

@end

int main() {
  [[TestNotificationCenter alloc] init];
  return 0;
}