如何清除IOS应用程序库缓存（下载的图像）

我正在处理下载异步图像。我从我的网络服务器获得了很多图像，但都是暂时的，我不会缓存它们中的任何一个。但该应用程序显然将下载图像保存在/ Library / Caches中。我该如何解决？

I am working with download async images. I get a lot images from my webserver but all are temporary and I won't cache any of them. But the app apparently save the download images in /Library/Caches. How can I resolve that?

有没有办法阻止缓存下载的图像？或者从缓存中删除它们？

Are there any way to prevent cache downloaded images? Or delete them from cache?

我尝试了这两种不同的方法：

I tried these two different methods:

#pragma mark - Method 1

- (void)method1{
    NSURL *imageURL = [NSURL URLWithString:self.photoLink];
    [self setImage:[UIImage imageNamed:@"nut"] forState:UIControlStateNormal];
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
        dispatch_async(queue, ^{
        NSData *data = [NSData dataWithContentsOfURL:imageURL options:NSDataReadingUncached error:NULL];
        dispatch_async(dispatch_get_main_queue(), ^{
            [self setImage:[UIImage imageWithData:data] forState:UIControlStateNormal];
            });
        });
    //}
}

#pragma mark - Method 2

- (void)method2{

    NSOperationQueue *queue = [[NSOperationQueue alloc]init];

    // The Placeholder
    [self setImage:[UIImage imageNamed:@"nut"] forState:UIControlStateNormal];

    NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self
                                                                            selector:@selector(loadDataAsyc)
                                                                              object:nil];
    [queue addOperation:operation];

    [operation release];
}
-(void)loadDataAsyc{

    // create a local autorelease pool since this code runs not on main thread
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:self.photoLink] options:NSDataReadingUncached error:NULL];
    UIImage *image = [UIImage imageWithData:data];

    [self performSelectorOnMainThread:@selector(showImage:) withObject:image waitUntilDone:NO];

    [pool release];
}
-(void)showImage:(UIImage *)image{
    [self setImage:image forState:UIControlStateNormal];
}