UIImage不释放内存

Question

我对内存管理有一个奇怪的问题让我发疯。我需要异步预加载图像。我有一个代码

- (void)preloadFinishAnimation
{
    self.animationImages = [NSMutableArray new];
    __weak LearningViewController *weakSelf = self;

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        for (int i = 0; i < NUMBER_OF_ANIMATION_FRAMES; i++) {
            UIImage *problemImage = [UIImage imageNamed:[NSString  stringWithFormat:@"success-%d", i]];
            [weakSelf.animationImages addObject:[weakSelf renderedImageFromImage:image]];
            problemImage = nil;
        }
    });
}


- (UIImage *)renderedImageFromImage:(UIImage *)image
{
    UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0);
    CGRect rect = CGRectMake(0, 0, image.size.width, image.size.height);
    [image drawInRect:rect];
    UIImage *renderedImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return renderedImage;
}

我用Instruments检查过，我知道problemImage不会释放内存。以下是problemImages之一的retain / release命令。

希望有人知道问题出在哪里！

Answer 1

您必须使用imageWithContentsOfFile:或initWithContentsOfFile:代替imageNamed:，因为imageNamed:将始终缓存图像，直到系统请求更多内存并清除缓存的图像。

Answer 2

UIImage imageNamed：缓存图像并按照自己的计划释放内存。 使用“imageWithContentsOfFile”：

[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil]]