如何在UIPickerView中更改所选行的颜色 [英] How to change color of selected row in UIPickerView

问题描述

好吧，也许我错过了一些非常简单的事情，如果是这种情况我会道歉，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分量选择器视图中的行视图。所以我认为这样可行：

Ok, maybe I'm missing something really simple and I apologize if that's the case, however, I've googled every permutation of the title and have not found! So this is simply what I want to do: change the background color of the label I'm using as the row view in a 2 component pickerview when that row has been selected. So I thought this would work:

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！非常感谢任何建议!!

but this doesn't work. It seems to arbitrarily choose which row to color and sometimes even give a bad access error. I've tried all different clauses to no effect! ANy suggestions would be greatly appreciated!!

以下是完整方法：

- (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;
}

推荐答案

解决了！声明2个实例变量：selectedView和oldView。然后下面的代码可以解决这个问题：

Solved! Declare 2 instance variables: selectedView, and oldView. Then the following code does the trick:

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;

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