How do I get around NSCocoaErrorDomain:257 when pulling a file from the Files app?

Question

I'm trying to access a file to pull a copy into my app so that users can associate it with relevant information. It used to work just fine up until recently, and now I suddenly am getting the following message:

Failed to read file, error Error Domain=NSCocoaErrorDomain Code=257 "The file “[File name]” couldn’t be opened because you don’t have permission to view it." UserInfo={NSFilePath=/private/var/mobile/Library/Mobile Documents/com~apple~CloudDocs/[File name], NSUnderlyingError=0x281b88690 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}}

This is the code that's throwing the error:

//AppDelegate.m
-(BOOL)application:(UIApplication *)app openURL:(NSURL *)url options:(NSDictionary<UIApplicationOpenURLOptionsKey,id> *)options
{
    if (![url.pathExtension isEqualToString:@"pdf"] && ![url.pathExtension isEqualToString:@"png"] && ![url.pathExtension isEqualToString:@"jpg"] && ![url.pathExtension isEqualToString:@"jpeg"]){
        return false;
    }
    NSError* error = nil;
    NSString *path = [url path];
    NSData *data = [NSData dataWithContentsOfFile:path options: 0 error: &error];
    if(data == nil) {
        NSLog(@"Failed to read file, error %@", error);
    }

    //Do stuff with the file    

    return true;
}

I did update to xcode 11 and iOS 13, so there may have been a change there that I wasn't aware of.

Answer 1

Jordan has a great answer! Here's the version translated to Swift

let isAccessing = url.startAccessingSecurityScopedResource()

// Here you're processing your url

if isAccessing {
    url.stopAccessingSecurityScopedResource()
}

As I encountered this myself and the comment to Jordan's answer confirmed this happens only on the real device. Simulator has no such an issue