for (UIView *searchBarSubview in [mySearchBar subviews]) {
        if ([searchBarSubview conformsToProtocol:@protocol(UITextInputTraits)]) {
            @try {

                [(UITextField *)searchBarSubview setBorderStyle:UITextBorderStyleRoundedRect];
            }
            @catch (NSException * e) {
                // ignore exception
            }
        }
    }

mySearchBar.subviews().forEach { searchBarSubview in
  if searchBarSubview is UITextInputTraits {
    do {
        (searchBarSubview as? UITextField)?.borderStyle = .roundedRect
    } catch {
        // ignore exception
    }
  }
}

UIView *leftView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 10., nameField.bounds.size.height)];
nameField.leftView = leftView;
nameField.leftViewMode = UITextFieldViewModeAlways;
leftView release];

UITextField *txfSearchField = [_searchBar valueForKey:@"_searchField"];
txfSearchField.borderStyle = UITextBorderStyleNone;

UITextField * x = (UITextField*)searchBarSubview;
x.background = nil;

for (UIView *searchBarSubview in [search_bar subviews]) {
        if ([searchBarSubview conformsToProtocol:@protocol(UITextInputTraits)]) {
            if([searchBarSubview isKindOfClass:[UITextField class]])
            {
                [(UITextField *)searchBarSubview setBorderStyle:UITextBorderStyleRoundedRect];
            }
        }
    }

+ (void)setSearchBar:(UISearchBar *)searchBar cornerRadius:(CGFloat)radius {
    //set searchbar corner radius
    for(UIView *possibleSearchBarTextFieldSuperview in [searchBar subviews]) {
        if([[possibleSearchBarTextFieldSuperview subviews] count] > 0) {
            for(UIView *possibleInnerSearchBarTextField in [possibleSearchBarTextFieldSuperview subviews]) {
                if([possibleInnerSearchBarTextField conformsToProtocol:@protocol(UITextInputTraits)]) {
                    possibleInnerSearchBarTextField.layer.cornerRadius = radius;
                    possibleInnerSearchBarTextField.layer.masksToBounds = YES;
                    return;
                }
            }
        }
    }
}

let textFieldInsideUISearchBar = searchBar.value(forKey: "searchField") as? UITextField
    textFieldInsideUISearchBar?.borderStyle = .none
    textFieldInsideUISearchBar?.backgroundColor = UIColor.white