更改不同列的UIPickerView字体大小

Question

我正在构建一个UIPickerView,它可以正常使用我的代码.

//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,我想将字体大小更改为较小的字体.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;
    }

有没有快速的方法让我将上面的代码组合到我的可用代码中来改变字体大小？说,我想需要在某处传递"Retval"？

更新:感谢Scotts的提示(见下文),我的方法有效,发布在这里:

- (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,请使用您最初使用的条件pickerView:titleForRow:完全删除并在其中pickerView:viewForRow:设置retval文本pickerView:titleForRow:.

- (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,而不是创建一个标签子视图,你可以直接通过编辑标题的字体UIPickerViewDelegate的pickerView:attributedTitleForRow:forComponent:方法,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];
}