更改不同列的 UIPickerView 字体大小

Question

我正在构建一个 UIPickerView，它适用于我的以下代码。

//Title for Row
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{

    if (component==kNumComponent)
        return Number[row];
        else if(component==kSeaComponent)
            return Season[row];
        else
            return Course[row];

}

其中 Number、Season 和 Course 是存储字符串的 NSArray。在这里，我当然想将字体大小更改为更小的字体。我在这里学到了一些例子。

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row
forComponent:(NSInteger)component reusingView:(UIView *)view {
            UILabel *retval = (id)view;
            if (!retval) {
                retval= [[[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, [pickerView rowSizeForComponent:component].width, [pickerView rowSizeForComponent:component].height)] autorelease];
            }

            retval.font = [UIFont systemFontOfSize:22];
            retval.text = [pickerViewArray objectAtIndex:row];
       return retval;
    }

请问有什么快速的方法可以将上述代码合并到我的可用代码中以更改字体大小吗？说，我想需要在某个地方传递“Retval”？

更新：感谢 Scotts 的提示（见下文），我的方法有效，张贴在这里：

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

    UILabel *retval = (UILabel*)view;
    if (!retval) {
        retval = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, [pickerView rowSizeForComponent:component].width, [pickerView rowSizeForComponent:component].height)];
    }

    retval.font = [UIFont systemFontOfSize:22];

    if (component==kNumComponent)
        retval.text = Number[row];
    else if(component==kSeaComponent)
    {retval.font = [UIFont systemFontOfSize:14];
        retval.text = Season[row];}
    else
    { retval.font = [UIFont systemFontOfSize:14];
        retval.text = Course[row];}

    return retval;
}

Answer 1

要自定义选择器的视图，您必须使用pickerView:viewForRow:。为此，请完全删除pickerView:titleForRow:，并在pickerView:viewForRow: 中，使用您最初在pickerView:titleForRow: 中使用的条件设置retval 的文本。

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

        UILabel *retval = (UILabel*)view;
        if (!retval) {
            retval = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, [pickerView rowSizeForComponent:component].width, [pickerView rowSizeForComponent:component].height)];
        }

        retval.font = [UIFont systemFontOfSize:22];

        if (component==kNumComponent)
            retval.text = Number[row];
        else if(component==kSeaComponent)
            retval.text = Season[row];
        else
            retval.text = Course[row];

        return retval;
}

或者不用创建标签子视图，可以直接使用UIPickerViewDelegate的pickerView:attributedTitleForRow:forComponent:方法编辑标题的字体，例如：

- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    NSString *title;
    if (component==kNumComponent)
        title = Number[row];
    else if(component==kSeaComponent)
        title = Season[row];
    else
        title = Course[row];

    UIFont *font = [UIFont systemFontOfSize:22];
    NSDictionary *attributes = @{NSFontAttributeName:font};

    return [[NSAttributedString alloc] initWithString:title attributes:attributes];
}