Question

I’m trying to compile application on my iPad. I’m using AFNetworking to get list of files on my FTP. Application works on simulator, but when i start it on iPad i get (null) content of file with list. Here’s code:

- (void) getListOfFiles {

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL  URLWithString:@"ftp://anonymous@ftphost/"]];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

NSString *path = [[[NSBundle mainBundle]resourcePath]stringByAppendingPathComponent:@"list"];

operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:YES];


[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, NSHTTPURLResponse *response) {
         NSLog(@"Success %@",operation.response);
}
            failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                NSLog(@"Error: %@", [error localizedDescription]);
                                 }];

[operation start];
NSString *content  = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding  error:nil];

NSLog (@"%@",content);
}

So variable content = (null) only on iPad, and on Simulator everything is fine. Please help, i have lost any hope )

Answer 1

the AFHTTP*Operations are all asynchronous by default.

this is proper, since synchronous(blocking) calls block the main thread

you are starting the operation and take file content directly afterwards. This can’t work reliably because the start call is ASYNC and only STARTS the op but doesnt wait for it

either wait for it … which is BAD as it blocks the thread:

[operation start];
[operation waitUntilDone];

or MUCH BETTER modify getFiles to work asynchronously:

- (void) getListOfFiles {
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL  URLWithString:@"URL"]];
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

    NSString *path = [[[NSBundle mainBundle]resourcePath]stringByAppendingPathComponent:@"list"];
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:YES];


    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, NSHTTPURLResponse *response) {
             NSLog(@"Success %@",operation.response);
             NSString *content  = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding  error:nil];
             NSLog (@"%@",content);
        }
        failure:^(AFHTTPRequestOperation *operation, NSError *error) {
            NSLog(@"Error: %@", [error localizedDescription]);
        }];

    [operation start];
}