public class childA : Parent{

  //written in swift
}
public class childB : Parent{
  //written in swift
}

@interface Parent @end
@implementation Parent
   //written objective c
   - (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self initialize];
    }
    return self;
}

- (instancetype)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        [self initialize];
    }
    return self;
}

@end

let cA = childA.Type
       cA.init() // here default initWithCoder the Parent class

   let cB = childB.Type
       cB.init() // here for some reason it calls initWithFrame