Show the unhighlightDeselected method for "Build a World Clock in Objective-C."

ViewController.m

-(void)unhighlightDeselected { 
  NSArray *cities = [@[self.nyc, self.paris, self.moscow,  self.hongKong, self.honolulu, self.seattle]mutableCopy];
  NSMutableArray *unselectedCities = [NSMutableArray array];
     
  for (UIButton *city in cities) {
      if (city != self.selectedButton) {
      [unselectedCities addObject:city];
      }
  }
  [unselectedCities setValue:[UIColor blueColor] forKey:@"tintColor"];
}