UIPickerView去掉背景上的黑线

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view;

{

    UILabel* pickerLabel = (UILabel*)view;

    if (!pickerLabel){

        pickerLabel = [[UILabel alloc] init];

        pickerLabel.font=[UIFont systemFontOfSize: weight:];

        pickerLabel.textColor=[UIColor whiteColor];

        pickerLabel.textAlignment=;

        [pickerLabel setBackgroundColor:[UIColor clearColor]];

    }

    pickerLabel.text=[self pickerView:pickerView titleForRow:row forComponent:component];

    //在该代理方法里添加以下两行代码删掉上下的黑线

    [[pickerView.subviews objectAtIndex:] setHidden:TRUE];

    [[pickerView.subviews objectAtIndex:] setHidden:TRUE];

    return pickerLabel;

}