How to correctly provide networking feedback to the user? [closed] - iphone

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Closed 10 years ago.
My app retrieves currency exchange rates from a web service using a synchronous NSURLConnection in a background GCD queue, like this:
// This method is called in background queue
- (NSData*)fetchDataWithURLStr:(NSString*)urlStr {
NSData *jsonData = nil;
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
NSURL *url = [NSURL URLWithString:urlStr];
NSURLResponse *response = nil;
NSError *error = nil;
NSURLRequest *request = [NSURLRequest requestWithURL:url];
jsonData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
if (error != nil) {
NSString *errorMsg = nil;
NSInteger ec = [error code];
if (ec == NSURLErrorTimedOut || ec == NSURLErrorCannotConnectToHost) {
errorMsg = #"Data temporarily not available.";
}
// Call on main thread
dispatch_async(dispatch_get_main_queue(), ^{
// Present the error
[self showErrorWithCode:ec title:#"ERROR" message:errorMsg];
});
jsonData = nil;
}
return jsonData;
}
But the problem is often the app tries to fetch data, and the download seems to be running forever and nothing happens. No status updates just nothing. Often my WiFi is just stalled and I must go to Settings, disable and re-enable this. Or internet connectivity of my WiFi router at home is down but the device is connected to WiFi.
What I really want to do is give precise feedback about what exactly is happening on the network right now. For example
"Trying to contact server..."
"Wait... still trying..."
"Your internet seems broken..."
"Trying again..."
"Response received..."
"Downloaded 20%"
"Downloaded 40%"
"Finished!"
Just exact feedback about what is going on.
Someone recommended MKNetworkKit but it just feels as dead, no feedback whatsoever.
Are there solutions to this problem which work for iOS?
EDIT: I have Reachability in place but it does not give me this kind of feedback I want to display during networking. Also, Reachability does not tell me what is going on when there is a WiFi connection but the internet is stalled.

Answer 1

The fundamental problem here is that it is impossible (yes impossible) to give a reliable diagnosis of a network problem based on the information that is available to your app. There are simply too many possible causes, and some of them are simply not distinguishable without knowledge of the actual networks and / or access to other sources of diagnostic information.

Answer 2

U can user Reachability classes.
Here is a sample code which uses this reachability classes, and notifies us which type connection we are using. The sample code is from apple.
Have a look at & implement in the same way.
In order for showing the progress to the user, i suggest to use NSURLConnection from the its delegate methods you can easily get the status of the connection/request.
In one of its delegate it gives error description.

Answer 3

You should use the asynchronous API instead. Using the synchronous API in a separate worker thread/queue is often not the right way to go (see the WWDC'12 videos about those subjects)
A better solution would be to use the newer NSURLConnection API and the +sendAsynchronousRequest:queue:completionHandler: method instead of using sendSynchronousRequest: returningResponse: error:. This way you would avoid blocking your API and be informed when the request fails (either fails starting or fails while running because the network went down etc).
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse*, NSData*, NSError*) {
// Code that will be executed asynchronously
// when the response to the request has been received
}];
// After the call to this method above, the code will continue executing
// WITHOUT WAITING for the network request to have its response.
This way your UI won't "freeze" and the rest of your code will continue to run, so you can, like, show some progress indicator on your views for example, and so on. The code in the completionHandler block will be called asynchronously (independently of the rest of your code) only once the response has arrived.
Moreover, to be informed when the network itself is unreachable (went down, etc), use Reachability for that [EDIT] You seem to do this already as you added in the EDIT of your question, so you should already be informed about that and being able to inform the user in this case)
Tip: you may also use some third party frameworks, like the excellent [AFNetworking(https://github.com/AFNetworking/AFNetworking), that allows you to do much more when sending network requests, like having an Objective-C block of code to be called while the network request is in progress, allowing you to know the progression of the download easily.
Once you have integrated the AFNetworking project in your workspace, you would be able to do stuff like this:
AFHTTPRequestOperation* reqOp = [[[AFHTTPRequestOperation alloc] initWithRequest:request] autorelease];
[reqOp setCompletionBlockWithSuccess: ^(AFHTTPRequestOperation *operation, id responseObject)
{
// Code to execute asynchronously when you successfully received the whole page/file requested
// The received data is accessible in the responseObject variable.
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// Code to execute asynchronously when you request failed, for example if you have a network error, or received some 404 error code, etc.
progressLabel.text = [NSString stringWithFormat:#"Download error: %#", error];
}];
[reqOp setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead)
{
// Code to execute periodically each time a partial chunk of data is received
// So that you can update your progression. For example:
progressLabel.text = [NSString stringWithFormat:#"Downloading %.1f%%", (float)totalBytesRead*100.f/totalBytesExpectedToRead];
}];
[reqOp start]; // start the request
// The rest of the code will continue to execute, and the blocks mentioned above will be called asynchronously when necessary.

Answer 4

Here is how i check for internet connection . You need to add the Reachability first .
+ (BOOL) checkNetworkStatus
{
Reachability *reachability = [Reachability reachabilityForInternetConnection];
NetworkStatus networkStatus = [reachability currentReachabilityStatus];
return !(networkStatus == NotReachable);
}