iOS UIImageView 内存未在 ARC 上释放

Question

我想在圆形路径中为 ImageView 设置动画，并在单击图像时 ImageView 需要更改新图像。我的问题是我分配给 ImageView 的图像没有被释放。并且应用程序收到内存警告并崩溃。我浏览并尝试了很多解决这个问题的方法，但没有用。在我的例子中，我需要从 Objective c 类创建所有 ui 组件。这里发布创建 ImageView 和动画的代码。

@autoreleasepool {
    for(int i= 0 ; i < categories.count; i++)
    {
        NSString *categoryImage = [NSString stringWithFormat:@"%@_%ld.png",[categories objectAtIndex:i],(long)rating];
        if (paginationClicked) {
            if([selectedCategories containsObject:[categories objectAtIndex:i]]){
                categoryImage = [NSString stringWithFormat:@"sel_%@",categoryImage];
            }
        }
        UIImageView *imageView = [[UIImageView alloc] init];

        imageView.image = [self.mySprites objectForKey:categoryImage];
        imageView.contentMode = UIViewContentModeScaleAspectFit;
        imageView.clipsToBounds = NO;
        [imageView sizeToFit];
        imageView.accessibilityHint = [categories objectAtIndex:i];
//        imageView.frame = CGRectMake(location.x+sin(M_PI/2.5)*(self.view.frame.size.width*1.5),location.y+cos(M_PI/2.5)*(self.view.frame.size.width*1.5) , 150, 150);
        imageView.userInteractionEnabled = YES;
        imageView.multipleTouchEnabled = YES;
        UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self
                                                                                    action:@selector(categoryTapGestureCaptured:)];
        singleTap.numberOfTapsRequired = 1;
        [imageView addGestureRecognizer:singleTap];
        [categoryView addSubview:imageView];

        CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];

        UIBezierPath *path = [UIBezierPath bezierPath];
        [path addArcWithCenter:location
                        radius:self.view.frame.size.width*1.5
                    startAngle:0.8
                      endAngle:-0.3+(0.1*(i+1))
                     clockwise:NO];

        animation.path = path.CGPath;
        imageView.center = path.currentPoint;
        animation.fillMode              = kCAFillModeForwards;
        animation.removedOnCompletion   = NO;
        animation.duration              = 1+0.25*i;
        animation.timingFunction        = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];

        // Apply it
        [imageView.layer addAnimation:animation forKey:@"animation.trash"];
   }
    }

这是在点击时更改图像的代码。

for (UIImageView *subview in subviews) {
        NSString *key = [NSString stringWithFormat:@"%@_%ld.png",subview.accessibilityHint,(long)rating];
        if ([SelectedCategory isEqualToString:subview.accessibilityHint]) {
            NSString *tempSubCategory = [categoryObj objectForKey:SelectedCategory];
            if([selectedCategories containsObject:SelectedCategory]){
                subview.image = [self.mySprites objectForKey:key];
                [selectedCategories removeObject:SelectedCategory];
                if (tempSubCategory.length != 0) {
                    subCategoriesAvailable = subCategoriesAvailable-1;
                }
                [self showNoPagination:subCategoriesAvailable+2];
            }else{
                if(selectedCategories.count != 2){
                key = [NSString stringWithFormat:@"sel_%@",key];
                subview.image = [self.mySprites objectForKey:key];
                [selectedCategories addObject:SelectedCategory];
                    if ([SelectedCategory isEqualToString:@"Other"]) {
                        [self showCommentDialog];
                    }else{
                        if (tempSubCategory.length != 0) {
                            subCategoriesAvailable = subCategoriesAvailable+1;
                        }
                        [self showNoPagination:subCategoriesAvailable+2];
                    }
                }
            }
            [self disableCategories];
            break;
        }
    }

而且我不知道这里做错了什么。我尝试使 for 循环无效，但没有用。

我用来删除 ImageView 的代码

UIView *categoryView = [self.view viewWithTag:500];
    NSArray *subviews = [categoryView subviews];
    for (UIImageView *subview in subviews) {
        if(![selectedCategories containsObject:subview.accessibilityHint]){
            [subview removeFromSuperview];
            subview.image = Nil;
        }
    }

添加 Sprite 阅读器代码以供引用

#import "UIImage+Sprite.h"
#import "XMLReader.h"

@implementation UIImage (Sprite)

+ (NSDictionary*)spritesWithContentsOfFile:(NSString*)filename
{
    CGFloat scale = [UIScreen mainScreen].scale;
    NSString* file = [filename stringByDeletingPathExtension];
    if ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] && 
        (scale == 2.0))
    {
        file = [NSString stringWithFormat:@"%@@2x", file];
    }
    NSString* extension = [filename pathExtension];
    NSData* data = [NSData dataWithContentsOfFile:[NSString stringWithFormat:@"%@.%@", file,extension]];
    NSError* error = nil;
    NSDictionary* xmlDictionary = [XMLReader dictionaryForXMLData:data error:&error];
    NSDictionary* xmlTextureAtlas = [xmlDictionary objectForKey:@"TextureAtlas"];
    UIImage* image = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@.%@", file,[[xmlTextureAtlas objectForKey:@"imagePath"]pathExtension]]];
    CGSize size = CGSizeMake([[xmlTextureAtlas objectForKey:@"width"] integerValue],
                             [[xmlTextureAtlas objectForKey:@"height"] integerValue]);

    if (!image || CGSizeEqualToSize(size, CGSizeZero)) return nil;
    CGImageRef spriteSheet = [image CGImage];
    NSMutableDictionary* tempDictionary = [[NSMutableDictionary alloc] init];

    NSArray* xmlSprites = [xmlTextureAtlas objectForKey:@"sprite"];
    for (NSDictionary* xmlSprite in xmlSprites)
    {
        CGRect unscaledRect = CGRectMake([[xmlSprite objectForKey:@"x"] integerValue],
                                         [[xmlSprite objectForKey:@"y"] integerValue],
                                         [[xmlSprite objectForKey:@"w"] integerValue],
                                         [[xmlSprite objectForKey:@"h"] integerValue]);
        CGImageRef sprite = CGImageCreateWithImageInRect(spriteSheet, unscaledRect);
        // If this is a @2x image it is twice as big as it should be.
        // Take care to consider the scale factor here.
        [tempDictionary setObject:[UIImage imageWithCGImage:sprite scale:scale orientation:UIImageOrientationUp] forKey:[xmlSprite objectForKey:@"n"]];
        CGImageRelease(sprite);
    }

    return [NSDictionary dictionaryWithDictionary:tempDictionary];
}

@end

请帮我解决这个问题。提前致谢。

Answer 1

看起来所有图像都被字典(假设)self.mySprites 保留，因为您正在通过调用 imageView.image = [self.mySprites objectForKey: categoryImage];

如果您使用 +[UIImage imageNamed:] 将图像加载到字典中，那么字典最初只包含压缩的 png 图像。图像在呈现到屏幕时从 png 解压缩为位图，并且这些解压缩的图像使用大量 RAM(这是您看到的标记为“ImageIO_PNG_Data”的内存使用情况)。如果字典保留了它们，那么每次在屏幕上呈现一个新数据时内存都会增加，因为解压缩的数据保存在字典保留的 UIImage 对象中。

可供您选择的选项:

• 将图像名称存储在self.mySprites 字典中，并按需加载图像。您应该知道 +[UIImage imageNamed:] 实现了内部 RAM 缓存以加快速度，因此如果图像很大，这也可能会导致内存问题，因为缓存不会很快清除.如果这是一个问题，请考虑使用 +[UIImage imageWithContentsOfFile:]，尽管它需要一些额外的代码(不多)，它不会在 RAM 中缓存图像。

• 将 self.mySprites 重新实现为 NSCache。当内存压力过高时，NSCache 将开始抛出一些东西，因此您需要处理图像在您期望的时候不存在的情况，并从磁盘加载它(也许使用上述技术)