如何在UIPickerView中更改所选行的颜色

Question

好吧,也许我错过了一些非常简单的事情,如果是这样的话我会道歉,但是,我已经搜索了标题的每一个排列并且没有找到!所以这就是我想要做的事情:当选择该行时,将我正在使用的标签的背景颜色更改为2组件选择器视图中的行视图.所以我认为这会奏效:

if (row == [pickerview selectedRowForComponent])
    viewlabel.backgroundColor = redcolor;

但这不起作用.它似乎随意选择要着色的行,有时甚至会给出错误的访问错误.我试过所有不同的条款都没有效果!任何建议将不胜感激!!

这是完整的方法:

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

    if (component == kNumberComponent) {


#define PICKER_LABEL_FONT_SIZE 24
#define PICKER_LABEL_ALPHA 1.0
        // UIFont *font = [UIFont boldSystemFontOfSize:PICKER_LABEL_FONT_SIZE];
        UIFont *font = [ UIFont fontWithName:@"AppleGothic"  size:24];
        UILabel *carsLabel =[ [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 75, 50) ]autorelease];
        //[picker selectRow:row inComponent:component animated:YES];
        NSString *pickerText = [self.numbers objectAtIndex:(int)row];
        carsLabel.text = pickerText;
        carsLabel.textAlignment = UITextAlignmentCenter;
        NSLog(@"carsLabel = %@",carsLabel.text);
        //carsLabel.text = @"maybe because the string isn't long enough";
        carsLabel.textColor = [UIColor blackColor];
        carsLabel.font = font;





        carsLabel.opaque = YES;


        [view addSubview:carsLabel];

        return carsLabel;   
    } else {
        UIFont *font = [ UIFont fontWithName:@"AppleGothic"  size:18];

        UILabel *carsLabel = [[[UILabel alloc] initWithFrame:CGRectMake(0, 0, 225, 50)] autorelease];
        id fact = [self.facts objectAtIndex:(int)row];
        NSString *pickerText = @"Dictionary Entry";
        if ( [fact isKindOfClass:[NSString class]]) {


            pickerText = [self.facts objectAtIndex:(int)row];

        } 
        carsLabel.text = pickerText;
        carsLabel.textAlignment = UITextAlignmentCenter;
        NSLog(@"carsLabel = %@",carsLabel.text);
        //carsLabel.text = @"maybe because the string isn't long enough";
        carsLabel.textColor = [UIColor blackColor];
        carsLabel.font = font;
        if ( row == 0) {
        carsLabel.backgroundColor = [UIColor redColor];

        }
        //carsLabel.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"blackboard.png"]];;
        carsLabel.opaque = YES;

        [view addSubview:carsLabel];

        return carsLabel;
    }


    return nil;
}

Answer 1

通常,我使用这种方法:

我使用自定义视图来显示行项目

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

    UILabel *label = (id)view;

    if (!label)
    {

        label= [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, [pickerView rowSizeForComponent:component].width, [pickerView rowSizeForComponent:component].height)];
        label.textAlignment = NSTextAlignmentCenter;
        label.textColor = [UIColor whiteColor];
        label.text = _arrayStringPicker[row];

    }  

    return label;

我改变选择的行的颜色:

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

    UILabel *labelSelected = (UILabel*)[pickerView viewForRow:row forComponent:component];
    [labelSelected setTextColor:[UIColor redColor]];

}

Answer 2

viewForPicker的正确格式是:

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
    UILabel *label = (UILabel*) view;
    if (label == nil)
    {
        label = [[UILabel alloc] init];
    }

    [label setText:@"Whatever"];

    // This part just colorizes everything, since you asked about that.

    [label setTextColor:[UIColor whiteColor]];
    [label setBackgroundColor:[UIColor blackColor]];
    CGSize rowSize = [pickerView rowSizeForComponent:component];
    CGRect labelRect = CGRectMake (0, 0, rowSize.width, rowSize.height);
    [label setFrame:labelRect];

    return label;
}

上面代码的问题是:它使标签着色,而不是选择器本身.因此,当您滚动到一端或另一端时,会有一个空白点,您可以看到白色背景.设置[myPicker setBackgroundColor ...]并不能达到人们所希望的效果.

Answer 3

Swift 实现

extension PickerViewController: UIPickerViewDelegate {
    func pickerView(pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
        var color: UIColor!
        if pickerView.selectedRowInComponent(component) == row {
            color = UIColor.redColor()
        } else {
            color = UIColor.blackColor()
        }

        let attributes: [String: AnyObject] = [
            NSForegroundColorAttributeName: color,
            NSFontAttributeName: UIFont.systemFontOfSize(15)
        ]

        return NSAttributedString(string: rows[row], attributes: attributes)
    }

    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        //this will trigger attributedTitleForRow-method to be called
        pickerView.reloadAllComponents()
    }
}

Answer 4

解决了！声明 2 个实例变量：selectedView 和 oldView。然后下面的代码就可以解决问题：

if (self.oldView != nil)
        self.oldView.backgroundColor = [UIColor clearColor];

self.selectedView = [picker viewForRow:row forComponent:kNumberComponent];
        self.selectedView.backgroundColor = [UIColor redColor];
        [self.selectedView setNeedsDisplay];
        self.oldView = self.selectedView;