Ios 选择时，PickerView didSelectRow将崩溃并显示（lldb）错误

我正在创建自定义视图，因为我添加了选择器，当选择了

后，我将从superView中删除选择器，但应用程序将崩溃。如果不从
superview
中删除，则不会崩溃。我能做什么请给我提个建议

当选择文本字段时，我将使用选择器

 _rUsername=[[UITextField alloc]initWithFrame:CGRectMake(15, 270, self.view.frame.size.width-30, 30)];
            _rUsername.backgroundColor=[UIColor whiteColor];
            _rUsername.placeholder=@"Gander";
            [_rUsername addTarget:self action:@selector(showPicker)forControlEvents:UIControlEventEditingDidBegin];
[_registerView addSubview:_rUsername];

现在是选择器方法中的问题

-(void) showPicker
{
    [_rUsername resignFirstResponder];
   UIPickerView *pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(30,230,220,0)];

    pickerView.delegate = self;
    pickerView.dataSource = self;
    pickerView.showsSelectionIndicator = YES;
    [_registerView addSubview:pickerView];
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return [_arrayNo count];
}
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView     {
    return 1;
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
     return [_arrayNo objectAtIndex:row];
}
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {
    int sectionWidth = 300;
    return sectionWidth;
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{

    _rUsername.text=[_arrayNo objectAtIndex:row];
     [pickerView removeFromSuperview];

}

如果我删除了
[pickerView removeFromSuperview]
from
didselectRow
方法它将正常工作，但我希望在选择选择器后必须从superview中删除它。如果它不会崩溃，就会像这样显示错误“（lldb）”
 将其更改为以下内容：

pickerView.hidden = true;

使用此项—
[pickerView setHidden:是]