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我正在使用下载异步图像。我从我的网络服务器获得了很多图像，但都是临时的，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？

有什么方法可以防止缓存下载的图像？或者从缓存中删除它们？

我尝试了这两种不同的方法： 

#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];
}
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1 回答 1

0

缓存将在需要时清空，即当应用程序收到内存不足警告时。您没有理由自己这样做，也没有可用的公共 API。

注意
当操作系统为您管理某些事情时，您无需担心。

但是，如果您真的想清除缓存，请按照此操作

NSFileManager *filemgr;

filemgr = [NSFileManager defaultManager];

if ([filemgr removeItemAtPath: [NSHomeDirectory() stringByAppendingString:@"/Library/Caches"] error: NULL]  == YES)
    NSLog (@"Remove successful");
else
    NSLog (@"Remove failed");

[filemgr createDirectoryAtPath: [NSHomeDirectory() stringByAppendingString:@"/Library/Caches"] withIntermediateDirectories:NO attributes:nil error:nil];
于 2013-02-16T12:10:29.310 回答