依赖 UIPickerView

Question

有谁知道如何制作依赖 UIPickerView.例如，当我选择组件一的第 2 行时，组件二的标题会发生变化吗？

我在互联网上查看过，没有真正的答案，我尝试过使用 if 和 switch 语句，但它们只是崩溃了。

Answer 1

这取决于您将如何保存数据。例如，如果您有一个数组作为字典键的值，并且该字典具有不同的此类键，则第一列将是键，选择一个数组后，您将在另一列（组件）。 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView 方法应返回 2。
在
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
方法中，您需要给出组件 1 的字典中键的数量，以及当前所选键的数组的数量。
例如

if(component==0) return [[DICTIONARY allKeys] count];
else return [[DICTIONARY objectForKey:@"SELECTED_KEY"] count];

然后，

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

    selectedIndex = [pickerView selectedRowInComponent:0];
    if (component == 1 && !(selectedIndex < 0)) {
        [pickerView reloadComponent:2];

        [pickerView selectRow:0 inComponent:2 animated:YES];
    }

}

和

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

    UILabel *pickerRow = (view != nil) ? view : [[[UILabel alloc] initWithFrame:CGRectMake(5, 0, 115, 60)] autorelease];
    pickerRow.font = [UIFont boldSystemFontOfSize:14];
    pickerRow.textAlignment = UITextAlignmentLeft;
    pickerRow.backgroundColor = [UIColor clearColor];
    pickerRow.textColor = [UIColor blackColor];
    pickerRow.numberOfLines = 0;
    if (component == 0) {

        pickerRow.text = @"DICTIONARY_ROW'th_KEY";
    }
    else {

        pickerRow.text = [[dictionary objectForKey:@"SELECTED_KEY"] objectAtIndex:row];

    }
    return pickerRow;
}

Answer 2

我确信这可以使用委托方法 pickerView:didSelectRow:inComponent: 和 reloadComponents 的组合来完成。

Answer 3

希望这有帮助，我有类似的情况，我的要求是当我在组件中选择国家/地区名称时，该国家/地区的城市应加载到第二个组件中。所以我所做的是，我有 2 个并排的选择器视图，当用户在国家/地区选择器中选择一行时，我使用适当的数据重新启动第二个选择器。

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

    if (pickerView == countryPickerView)    
    {

        if(PickerViewCity)
        {
            [PickerViewCity removeFromSuperview];
            [PickerViewCity release];
            PickerViewCity=nil;
        }


        PickerViewCity = [[UIPickerView alloc] initWithFrame:CGRectMake(160, 38, 320, 240)];
        PickerViewArrayCity=[[countryPickerViewArray objectAtIndex:[pickerView selectedRowInComponent:0]]objectForKey:@"nodeChildArray"];
        //NSLog(@"%@",PickerViewArrayCity);
        PickerViewCity.showsSelectionIndicator = YES;   // note this is default to NO
        PickerViewCity.delegate = self;
        PickerViewCity.dataSource = self;
        CGAffineTransform s20 = CGAffineTransformMakeScale(0.5, 0.58);
        CGAffineTransform t21 = CGAffineTransformMakeTranslation(-80,-50);
        PickerViewCity.transform = CGAffineTransformConcat(s20, t21);
        PickerViewCity.layer.masksToBounds = YES;
        [someview addSubview:PickerViewCity];       
    }


    if (pickerView == PickerViewCity)   
    {


    }   
}

Answer 4

您需要为第一个组件的每一行（索引为0）设置条件并打开一个开关来选择每个索引，我做到了并为我工作：

on ...titleForRow:(NSinteger)row forComponent(NSInteger ）组件

{
    if (component == 0)  // this is first component from left to right
        return [arrayForFirstComponent objectAtIndex:row];
    if (component == 1)  // this is second component from left to right
        switch([pickerIBOutletAsYouNamedIt selectedRowInComponent:0])  // here you set content of component two depending on which row is selected from component 1
        {
             case 0:            // remember index starts at 0
                 return [arrayForComponent2ForRow1inComponent1 objectAtIndex:row];
                 break;
             //... and so on for each row in the component 1 (with index 0)
        }
}

记住：你还必须这样做
- ...numberOfRowsInComponent:(NSInteger)组件
并与
- ...didSelectRow:(NSInteger)行 inComponent:(NSInteger)组件
在他的最后一个中，在选择组件 0 处的行时，调用 [pikcerIBOutlet reloadComponent:1]

Answer 5

我认为，您喜欢在更改一个组件时更改另一个组件的相应项目。这也许是一个更好的解决方案。

代码：

- (void)pickerView:(UIPickerView *)pickerView
      didSelectRow:(NSInteger)row
       inComponent:(NSInteger)component {
    if (component == 0) {

        //Here First Part of the Pickerview is represented using 0.
        // dependentPicker is the Pickerview outlet

        [dependentPicker selectRow:row inComponent:1 animated:YES];
        [dependentPicker reloadComponent:1];
    }
    else
    {
        [dependentPicker selectRow:row inComponent:0 animated:YES];
        [dependentPicker reloadComponent:1];
    }
}

注意：当您使用此代码时，组件值必须由两个 NSArray 保存，并且两个数组中相应的依赖值的顺序必须相同。