Question

我有一个带有内部UIImageView的NSMutableArray。滚动动作后，我想更改某些UIImageView的图像，但不能。

这是我首先启动数组的方式：

NSMutableArray *dotsImageSliderList = [[NSMutableArray alloc]init];

for (int i=0; i<totalImages; i++)
{
   UIImageView *dot =[[UIImageView alloc] initWithFrame:CGRectMake(distance,2,5,5)];
   if (i==0)
   {
       dot.image=[UIImage imageNamed:@"dotselected.png"];
   }
   else
   {
       dot.image=[UIImage imageNamed:@"dotunselected.png"];
   }

   [dotsImageSliderList addObject:dot];
}

这是我检索UIImageView并尝试更改图像的方式：

-(void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
{
    [NSObject cancelPreviousPerformRequestsWithTarget:self];
    NSInteger pagenumber = scrollView.contentOffset.x / scrollView.bounds.size.width;
    NSLog(@"%zd", pagenumber);

    if (pagenumber < [dotsImageSliderList count])
    {
        for (int i=0; i<[dotsImageSliderList count]; i++)
        {
            UIImageView *view = [dotsImageSliderList objectAtIndex:pagenumber];
            if (i==pagenumber)
            {
                view.image=[UIImage imageNamed:@"dotselected.png"];
            }
            else
            {
                view.image=[UIImage imageNamed:@"dotunselected.png"];
            }
        }
    }
}

我不知道为什么图像不改变。你能发现错误吗？

Answer 1

在循环外初始化图像对象。

    NSMutableArray *dotsImageSliderList = [[NSMutableArray alloc]init];
    UIImage * selectedImage = [UIImage imageNamed:@"dotselected.png"];
    UIImage * unselectedImage = [UIImage imageNamed:@"dotunselected.png"];

    for (int i=0; i<totalImages; i++)
    {
       UIImageView *dot =[[UIImageView alloc] initWithFrame:CGRectMake(distance,2,5,5)];
       if (i==0)
       {
           dot.image=selectedImage;
       }
       else
       {
           dot.image=unselectedImage;
       }

       [dotsImageSliderList addObject:dot];
    }

Answer 2

超级愚蠢的错误。我必须更改此行：

UIImageView *view = [dotsImageSliderList objectAtIndex:pagenumber];

对此：

UIImageView *view = [dotsImageSliderList objectAtIndex:i];

无法从UIImageView更改图像

2 个答案: