按钮操作的选择器视图崩溃

Question

I have a picker view,when the row component of a picker view is selected,it navigates to a view,there I have a button changeGroup.On clicking the button the picker view must appear,but it is not happening!崩溃了

这是我的代码：

- (void)viewDidLoad
{
groupArr = [[[NSMutableArray alloc]initWithObjects:@"Family",@"Friends",@"Office",@"Acquaintances", nil]autorelease];
    agrpPicker.hidden  = YES;
}

#pragma mark-
#pragma mark PickerView Datasource

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    int number = 0;

    if (agrpPicker.hidden == NO) 
    {
        number = 1;
    }

    return number;
}
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    int count = 0;
    if (agrpPicker.hidden == NO) 
    {
        count = [self.groupArr count];
    }
    return count;
}

#pragma mark-
#pragma mark PickerView Delegate

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    NSString *str = [[[NSString alloc]init]autorelease];

    if (agrpPicker.hidden == NO) 
    {
        str = [self.groupArr objectAtIndex:row];
    }

    return str;
}

这是显示选择器视图的按钮的操作：

-(IBAction)groupButtonSelceted:(id)sender
{
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.6];
    CGAffineTransform transfrom = CGAffineTransformMakeTranslation(0, 200);
    agrpPicker.transform = transfrom;
    [UIView commitAnimations];
    agrpPicker.hidden = [agrpPicker isHidden] ? NO : YES;
    [self.view addSubview:agrpPicker];
}

将该选择器视图连接到 IB 中的选择器视图。

这是坠毁地点的屏幕截图

在控制台中，消息如下图所示：

哪位专家能指出我哪里出错了......

请帮我提出宝贵的建议，在此先感谢:)

对不起各位，我发现是什么错误，我没有在自动释放后保留数组，而不是：

groupArr = [[[NSMutableArray alloc]initWithObjects:@"Family",@"Friends",@"Office",@"Acquaintances", nil]autorelease];

是self.groupArr = ....;

感谢所有查看过的人和为解决问题做出贡献的人:)

Answer 1

由于自动释放，您的 groupArr 数组正在失去其内容。所以改变这个

groupArr = [[NSMutableArray alloc]initWithObjects:@"Family",@"Friends",@"Office",@"Acquaintances", nil];

[groupArr 保留];

Answer 2

在 .h 文件中添加 UIPickerViewDelegate。

在 .m 文件中，添加 PickerView 委托和数据源方法。 数据来源：

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;

代表：

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

有关详细信息，请参阅 Apple 的UIPickerView class。