Question

我想在UIPickerView组件中显示一组连续的数字，但它像Clock-＆gt; Timer应用程序的秒组件一样包围。我可以启用的唯一行为看起来像Timer应用程序的hours组件，您只能在一个方向滚动。

Answer 1

将行数设置为大数量同样容易，并使其从高值开始，用户很可能在很长一段时间内滚动滚轮 - 即便如此，更糟糕的是，它们会触底。

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    // Near-infinite number of rows.
    return NSIntegerMax;
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    // Row n is same as row (n modulo numberItems).
    return [NSString stringWithFormat:@"%d", row % numberItems];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    self.pickerView = [[[UIPickerView alloc] initWithFrame:CGRectZero] autorelease];
    // ...set pickerView properties... Look at Apple's UICatalog sample code for a good example.
    // Set current row to a large value (adjusted to current value if needed).
    [pickerView selectRow:currentValue+100000 inComponent:0 animated:NO];
    [self.view addSubview:pickerView];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    NSInteger actualRow = row % numberItems;
    // ...
}

Answer 2

我在这里找到了答案：

http://forums.macrumors.com/showthread.php?p=6120638&highlight=UIPickerView#post6120638

当它要求行的标题时，请给它：代码：

return [rows objectAtIndex:(row % [rows count])];

当它说用户didSelectRow：inComponent：时，请使用以下内容：

代码：

//we want the selection to always be in the SECOND set (so that it looks like it has stuff before and after)
if (row < [rows count] || row >= (2 * [rows count]) ) {
    row = row % [rows count];
    row += [rows count];
    [pickerView selectRow:row inComponent:component animated:NO];
}

看起来UIPickerView不支持原生包装，但你可以通过插入更多数据集来愚弄它，当选择器停止时，将组件居中到数据集的中间。

Answer 3

Just create an array multiple times, so that you have your numbers multiple times. Lets say when want to have the numbers from 0 to 23 and put that in an array. that we will do 10 times like this...

NSString *stdStepper;

    for (int j = 0; j<10; j++) {
        for(int i=0; i<24; i++)
        {
            stdStepper = [NSString stringWithFormat:@"%d", i];

            [_hoursArray addObject:stdStepper];

        }
    }

later we set the row 0 selected like this

[_hoursPickerView selectRow:120 inComponent:0 animated:NO];

Answer 4

所有答案都没有真正让选择器视图循环滚动。

我基于UIScrollView创建了一个循环表。基于此tableView，我重新实现了UIPickerView。您可能对此DLPickerView感兴趣。此选择器视图具有UIPickerView所具有的所有功能，但也提供了许多新功能，并且自定义此选择器视图更加容易。

https://github.com/danleechina/DLPickerView

请注意，这个DLPickerView循环滚动实际上是在循环滚动。所有的魔法都是因为另一个班级DLTableView而发生的。

你如何使UIPickerView组件环绕？

4 个答案: