I am using ASIHTTPRequest (I know, I know, it is not being maintained - that doesn't matter; it works and it is what my app is built on) to run a series of HTTP requests through ASINetworkQueue.
The problem is that my queue will have many requests (thousands), and it will take a while to run. In the time that it is running, some of the data in the app may have changed which would make some of the request unnecessary. I would like to run a validation method on each request right before it runs, and if the validation method does not check out, then it will cancel that request and go on to the next one.
Right now, I am using the following code to create my ASIHTTPRequests:
ASINetworkQueue *myQueue = [ASINetworkQueue queue];
NSURL *URL = [NSURL URLWithString:#"http://mywebsite.com"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setStartedBlock:^{
NSLog(#"Request started: %#", request.url.absoluteString);
}];
[request setCompletionBlock:^{
NSLog(#"Request completed: %#", request.url.absoluteString);
// do some code here to clean up since it's finished
}];
[myQueue addOperation:request];
My current thinking is to put something into the startedBlock, so it would do:
[request setStartedBlock:^{
NSLog(#"Request started");
if (![self myValidationMethod]) {
[request cancel]; // <----------
}
}];
However when I do this, I get the following warning from Xcode:
"Capturing 'request' strongly in this block is likely to lead to a retain cycle."
First, is this the right method to go about doing this? I can't seem to find a way to remove a specific ASIHTTPRequest from an ASINetworkQueue. Second, is this warning from Xcode something that I will need to worry about?
About the warning you capture the blocks 'container' and form a cycle... just say:
__weak ASIHTTPRequest *rw = request;
and use that in the block.
as for the started block approach. doesnt sound perfect to me but I dont know a better approach...
Related
I am calling API continuously with 5 seconds interval using the following code:
NSURL *url=[NSURL URLWithString:#"any url"];
ASIFormDataRequest *request=[[ASIFormDataRequest alloc] initWithURL:url];
[request setRequestMethod:#"POST"];
[request setDelegate:self];
[request addRequestHeader:#"Accept" value:#"application/json"];
[request addPostValue:app.userName forKey:#"username"];
[request addPostValue:app.token forKey:#"token"];
[request setTimeOutSeconds:40];
[request startSynchronous];
NSError *error = [request error];
if (!error)
{ //sucesss
} "
The problem I have is after approximately 15-20 minutes, the app crashes with bad access error. I have enabled zombie objects but I didn't get any message on console. Am I doing anything wrong, or can you tell me a standard way to call an api continuously? Thanks.
Have you checked the app's memory usage? Is it possible that the way you are calling this every 5 seconds means that the objects you are alloc-initing aren't getting released, so you're just running out of memory? I'm assuming you're using NSTimer?
(On a second note, why are you using a delegate for a synchronous call? You can sometimes get odd errors if you don't unset them before they are released.)
In terms of standard ways to do this, the only thing I'd recommend is that you do this on a background thread then using notifications to update the UI.
Also, check your calling code as if you call this every 5 seconds, but with a 40 second timeout you could be stacking things up a bit (unless you stop the timer at the start, then reset it to 5 seconds at the end of this code).
This is a tough question.
When I press on the button, it is supposed to connect to a URL, which will initiate that method of my wcf service. However, when I debug, I noticed that the connection fails (like none of the delegate methods are called and stuff). I know that my WCF service works because when i type the URL in safari directly, it works perfectly, and performs that method. Here is my code:
- (IBAction)RBCButtonPressed:(id)sender {
//[[UIApplication sharedApplication] openURL:[NSURL URLWithString: #"http://10.1.51.55:8732/windows2/OnApplication?appName=RoyalBank.BankOfTheFuture.Surface.exe&directory=C:\\Program Files (x86)\\Bank of the Future"]];
NSString *urlString = #"http://10.1.51.55:8732/windows2/OnApplication?appName=RoyalBank.BankOfTheFuture.Surface.exe&directory=C:\\Program Files (x86)\\Bank of the Future";
NSLog(urlString);
NSURL *url = [NSURL URLWithString:urlString];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url ];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection release];
[request release];
if(connection)
self.valueReturned = [[NSData data] retain];
else
NSLog(#"data failed");
NSLog(#"connection failed");
[captureView addSubview:loader];
}
I'm not including the delegate methods cause they aren't called anyway.
It prints "connection failed."
UPDATE: When I use a method that takes in only one parameter, it works fine from both the browser and the device (the connection succeeds and the delegate methods are called). However, when there are two parameters, it works fine only from the browser. The connection always fails.
Possibilities - the use of the backslash confuses it somehow (?).
This is urgent and any help would be greatly appreciated.
EDIT: It will always print "connection failed" I realize, but I know that the connection fails because 1) the delegate methods aren't called and 2)the application does not turn on, which it will if the method is called.
If you check your NSURL object in the debugger, you'll find it's nil immediately after you try to initialize it. This is because it's malformed. Try URL encoding it first.
Notice the URL you pasted into safari changes to this:
http://10.1.51.55:8732/windows2/OnApplication?appName=RoyalBank.BankOfTheFuture.Surface.exe&directory=C:%5C%5CProgram%20Files%20(x86)%5C%5CBank%20of%20the%20Future
See all the %20s and %5Cs, etc.? That's because safari URL encodes it before sending the request. You must do the same.
Best regards.
It's failing because you are releasing connection right after you create it. If you're not using ARC, you could create it with autorelease, or just use ARC and forget about the releases.
I am having problems in my iphone application due to weak wifi signals. My application uses webservice to retireve data from our server but when Wifi signals are weak the response never comes back and user gets stuck on "Loading..." overlay screen. Finally the application crashes at the end. How can i handle this situation gracefully. Is there a way to set TimeOut for my webservice calls or something like this?
Thanks, Asif.
try to use ASIHTTP lib
http://allseeing-i.com/ASIHTTPRequest/How-to-use
You might want to learn about ASIHTTPRequest as it features much more than the standard CFNetwork api. The code is straight forward, error handling as well:
- (IBAction)grabURLInBackground:(id)sender
{
NSURL *url = [NSURL URLWithString:#"http://allseeing-i.com"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[request startAsynchronous];
}
- (void)requestFinished:(ASIHTTPRequest *)request
{
// Use when fetching text data
NSString *responseString = [request responseString];
// Use when fetching binary data
NSData *responseData = [request responseData];
}
- (void)requestFailed:(ASIHTTPRequest *)request
{
NSError *error = [request error];
}
You can set the NSURLConnection timeout and a delegate to respond to connection:didFailWithError: selector. See this S.O. topic.
if your delegate is never being called, this is a somehow known issue.
The only workaround seems to be setting your own NSTimer to fire after some time and cancel the request. It is definitely awkard, but it should not be that complex.
If you are curious about the reason behind the issue with timeout, it seems to be related to the slow starting of the 3G subsystem in an iPhone.
I was using NSURLConnection in a synchronous way before running on a background selector, so when I moved over to ASIHTTPRequest I did the same with this framework.
So, is it a bad idea to do something like the following?
// From another method
[self performSelectorInBackground:#selector(callDatasource) withObject:nil];
- (NSData *)callDatasource {
NSAutoreleasePool *apool = [[NSAutoreleasePool alloc] init];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:someURLthatIamusing];
[request setTimeOutSeconds:50.0];
[request startSynchronous];
NSError *error = [request error];
NSData *returnedData;
if (!error) {
returnedData = [request responseData];
} else {
// do something with error
}
[self performSelectorOnMainThread:#selector(done) withObject:nil waitUntilDone:NO];
[apool release];
return returnedData;
}//end
What would be the advantage to use the ASIHTTPRequest and asynchronous methods along with the delegate methods?
From experience, sometimes odd things can happen when using ASIHTTPRequest synchronous requests off a secondary thread: the download activity icon in the status bar not disappearing upon download completion is one issue I've noticed from time to time. I've had no major problems in the past, but I use the asynchronous methods now rather than your approach. The ASI asynchronous methods are by the nature of being a widely used library more highly tested than my own implementation could ever be.
There are a number of advantages with using the asynchronous methods - you mention the delegate methods, but the latest release of ASI actually also supports blocks, which is a great leap forward (dealing with multiple synchronous calls used to be a bit of a pain due to the shared delegate methods (or unique delegates for each asynchronous call). But with blocks you can now get rid of the delegates entirely. I've found them to be really useful. Plus if you use multiple contributors it can make readability a lot easier.
Also, by doing it Async, you can more easily track progress through the setProgressDelegate command.
i have one simple question, if i'm using ASIFormDataRequest when i need to release the request object?
NSURL *url = [NSURL URLWithString:#"url"];
ASIFormDataRequest *requestForm = [ASIFormDataRequest requestWithURL:url];
[requestForm addPostValue:[[NSUserDefaults standardUserDefaults] stringForKey:#"user"] forKey:#"user"];
[requestForm setRequestMethod:#"POST"];
[requestForm setDelegate:self];
[requestForm startAsynchronous];
Thanks
You need to remember that you are always responsible for releasing an object if the method from which you receive it contains new, copy, or init.
In this case, you don't need to release it. The ASIHTTPRequest class autoreleases it for you.
A quick search in the implementation file shows that it'll be autoreleased.
+ (id)requestWithURL:(NSURL *)newURL
{
return [[[self alloc] initWithURL:newURL] autorelease];
}
Your request is autoreleased in your code, so you don't need to release it (as others have said).
However, you are starting an asynchronous request - it'll complete/fail sometime in the future, and if it is associated with other objects which will get freed when the view exits you're potentially leaving yourself open to a crash. So I'd suggest you would want to make requestForm a property of your class (so when you assign the request to self.requestForm it will get retained for you), and explicitly release & nil it when the request completes.
If it's a very simple app with just one view you may get away without that though.