iOS-NSFileManager文件不存在

Question

I am hosting my in-app purchase content with Apple. I have managed to download the contents and right now I want to save it in device.

[[NSFileManager defaultManager] removeItemAtPath:dstPath error:nil];
[[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:dstPath error:nil];

This code above is how I move the content downloaded to my desired location.

It seems to work fine and when I try to display the content it works. But when I stop and run the app again the files does not exist.

What am I missing?

My code:

- (void)processDownload:(SKDownload *)download
{
    NSString *path = [download.contentURL path];

    path = [path stringByAppendingPathComponent:@"Contents"];

    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *files = [fileManager contentsOfDirectoryAtPath:path error:&error];

    NSMutableArray *stickersDownloadedArray = [[NSMutableArray alloc] init];

    for (NSString *file in files)
    {
        NSString *fullPathSrc = [path stringByAppendingPathComponent:file];

        NSString *fileName = [fullPathSrc lastPathComponent];
        NSString *fullPathDst = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:[NSString stringWithFormat:@"/%@", fileName]];

        [fileManager removeItemAtPath:fullPathDst error:nil];
        [fileManager moveItemAtPath:fullPathSrc toPath:fullPathDst error:nil];

        NSLog(@"fullPathDst: %@", fullPathDst);
        NSLog(@"file: %@", file);
        NSLog(@"key: %@", download.transaction.payment.productIdentifier);

        [stickersDownloadedArray addObject:fullPathDst];
    }

    [[NSUserDefaults standardUserDefaults] setObject:stickersDownloadedArray
                                              forKey:download.transaction.payment.productIdentifier];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

An example of fullPathDst is

/var/mobile/Containers/Data/Application/E921ADD6-B022-4DA2-8416-627DB44E679A/Documents/real4_12@2x.png

Answer 1

An app's sandbox changes at different times. You must never store full paths to files. Only store a relative path.

In your case, only store the path relative to the Documents folder. When you reload the relative path when the app starts up, you recalculate the full path again.