Question

应用程序假设在显示UICollectionView时崩溃。它还会创建一个低内存崩溃日志。如何减少UICollectionView中的内存使用量？我在项目中使用ARC。请帮忙......（以下是我的代码）

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
    return [untaggedImagesArray count];
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    @autoreleasepool {

    static NSString *identifier = @"imageCell";
    imageCell *cvc = (imageCell *)[self.iamgesCollectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
    if(cvc == nil){
        NSArray *topLevelObjects = [[NSBundle mainBundle]loadNibNamed:@"imageCell" owner:nil options:nil];
        for(id currentObject in topLevelObjects){
            if([currentObject isKindOfClass: [imageCell class]]){
                cvc = (imageCell*)currentObject;


                break;
            }
        }
    }
    NSString *path = [untaggedImagesArray objectAtIndex:indexPath.row];
         NSString *path = [untaggedImagesArray objectAtIndex:indexPath.row];
    //[self performSelectorInBackground:@selector(getImage:) withObject:path];

    UIImage *cache_image = [images_cache objectForKey:path];

    if(cache_image)
    {
        [cvc.imageView setImage:cache_image];
    }
    else
    {
        [self performSelectorInBackground:@selector(getImage:) withObject:path];
        //UIImage *img = [UIImage imageWithContentsOfFile:path];
        [images_cache setObject:cellImage forKey:path];
         [cvc.imageView setImage:cellImage];
    }


    if([preTaggedPaths containsObject:path]){
        [cvc.tagLabel setText:[tagStringsDict valueForKey:[NSString stringWithFormat:@"%d",indexPath.row]]];
        [cvc setUserInteractionEnabled:NO];
    }else{
        [cvc.tagLabel setText:@""];
        [cvc setUserInteractionEnabled:YES];
    }

        if([selectedImagesPath containsObject:path]){
            [cvc.checkImageView setImage:[UIImage imageNamed:@"checkbox_small_selected.png"]];
        }else{
            [cvc.checkImageView setImage:[UIImage imageNamed:@"checkbox_small_unselected.png"]];
        }

//
    return cvc;
    }
}



-(void)getImage:(NSString*)path{
    cellImage = [UIImage imageWithContentsOfFile:path];
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"clicked to select at index%d",indexPath.row);
    imageCell *cvc = (imageCell*)[self.iamgesCollectionView cellForItemAtIndexPath:indexPath];
    NSString *pathString = [untaggedImagesArray objectAtIndex:indexPath.row];
    [cvc.checkImageView setImage:[UIImage imageNamed:@"checkbox_small_selected.png"]];
    [selectedImagesPath addObject:pathString];
}

- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
     NSLog(@"clicked to DEselect at index%d",indexPath.row);
    imageCell *cvc = (imageCell*)[self.iamgesCollectionView cellForItemAtIndexPath:indexPath];
    NSString *pathString = [untaggedImagesArray objectAtIndex:indexPath.row];
    [cvc.checkImageView setImage:[UIImage imageNamed:@"checkbox_small_unselected.png"]];
    [selectedImagesPath removeObject:pathString];
//    [cvc setSelected:NO];
}

-

(void)getImage:(NSString*)path{
    //cellImage = [UIImage imageWithContentsOfFile:path];
    NSLog(@"image path: %@", path);
    cellImage = [UIImage imageNamed:path];

}

Answer 1

你说崩溃是由内存不足造成的！

可能出现的问题是图像加载机制（图像大小是多少？）：

[UIImage imageWithContentsOfFile:path];

每次为集合视图中的每个单元格执行此操作。

[UIImage imageNamed:@"name"];

例如缓存图像，而imageWithContentsOfFile则没有！

所以UIImage的方法imageNamed:和imageWithContentsOfFile做的事情略有不同。 imageNamed将图像加载到特殊的系统缓存中，然后使用该图像路径的未来调用将返回缓存中的图像，而不是从磁盘重新加载它。 imageWithContentsOfFile只是将图像加载到您指定的路径，但不进行缓存。对同一图像多次调用imageWithContentsOfFile将导致内存中有多个副本。

如果这是您的问题，请尝试缓存图像或使用智能方式仅加载此刻正在显示的图像。

UICollectionView在iPhone 3GS上的iOS 6.0上崩溃

1 个答案: