textfiled 修改clearbutton 图片按钮， 非rightview

UIButton *clearButton = [_textField valueForKey:@"_clearButton"];
    if (clearButton && [clearButton isKindOfClass:[UIButton class]]) {

        if ([DKNightVersionManager currentThemeVersion] == DKThemeVersionNormal) {
            [clearButton setImage:[UIImage imageNamed:@"Search-Topba-Close"] forState:UIControlStateNormal];
            [clearButton setImage:[UIImage imageNamed:@"Search-Topba-Close-Night"] forState:UIControlStateHighlighted];
        }else {
            [clearButton setImage:[UIImage imageNamed:@"Search-Topba-Close-Night"] forState:UIControlStateNormal];
            [clearButton setImage:[UIImage imageNamed:@"Search-Topba-Close-Highted-Night"] forState:UIControlStateHighlighted];
        }
    }