I put a NSMutableURLRequest request in dispatch_async but it doesn't work. However, NSURLRequest works. Code:
dispatch_queue_t queue1 = dispatch_get_global_queue(0, 0);
dispatch_async(queue1, ^{
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:#"http://google.com"]];
[request setHTTPMethod:#"GET"];
NSURLConnection* connection = [NSURLConnection connectionWithRequest:request delegate:nil];
[connection start];//It doesn't work!
//***
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://google.com"]];
NSURLResponse* theResponse = nil;
NSError* theError = nil;
NSData* data = [NSURLConnection sendSynchronousRequest:theRequest
returningResponse:&theResponse
error:&theError];
//This works great!
});
Is there any difference between NSMutableURLRequest and NSURLRequest? Or, I use the NSURLConnection in a wrong way?
Thanks!
It's not that you're using a mutable connection in one place and not the other, it's that you're calling the synchronous request method which runs immediately on the current thread versus an asynchronous method which needs a run loop to operate. From the documentation for -[NSURLConnection start]:
If you don’t schedule the
connection in a run loop or an operation queue before calling this
method, the connection is scheduled in the current run loop in the
default mode.
Calling the asynchronous method from a block on a background thread is redundant. You should either call the async method on the main thread (it returns immediately and schedules its work in the background) or call the synchronous method in the async dispatched block. Doing it the second way, you don't have to deal with all the delegate callbacks, but you give up some control over the load operation.
Related
I am trying to set up a cache, however the method I am using 'as below' is not being accessed by the thread.
- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse
I am initializing the connection like this, and connectionDidFinishLoading is accessed so I am not sure what I am missing.
- (IBAction)searchRequest:(NSData *)postBodyData
{
//Set database address
NSMutableString *databaseURL = [[NSMutableString alloc] initWithString:#"https://127.0.0.1:88"];
NSURL *url = [NSURL URLWithString:databaseURL];
NSString *postLength = [NSString stringWithFormat:#"%d", [postBodyData length]];
//SynchronousRequest to grab the data, also setting up the cachePolicy
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:5.0]; //if request dose not finish happen within 60 second timeout.
// NSInputStream *fileStream = [NSInputStream inputStreamWithData:postBodyData];
[request setHTTPMethod: #"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/octet-stream" forHTTPHeaderField:#"content-type"];
[request setHTTPBody:postBodyData];
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:request delegate:self];
if (theConnection) {
// Create the NSMutableData to hold the received data.
// receivedData is an instance variable declared elsewhere.
receivedData = [NSMutableData data];
} else {
// Inform the user that the connection failed from the connection:didFailWithError method
}
}
any help would be appreciated.
connection:willCacheResponse: is only called in cases when the response will be cached. POST requests are not cacheable in most cases. (More details: Is it possible to cache POST methods in HTTP?)
You should probably look at something like MKNetworkKit which handles a lot of this kind of caching, particularly for REST protocols.
You can also look at Drop-in offline caching for UIWebView. You'd have to modify it significantly, but NSURLProtocol can be used to solve this kind of problem. AFCache is currently working to integrate this approach, and is another toolkit to consider. (Read through the comments in the blog post for more background on the issues.)
I am using following code to download file from url's asynchronously,
NSMutableData *responseData = [[NSMutableData alloc] init];
NSURL *url = [NSURL URLWithString:#"http://www.tuiscos.com/images/trading.png"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
// do something with data
[responseData appendData:data];
myImage8.image = [UIImage imageWithData:data];
NSInteger len = response.expectedContentLength;
NSInteger receiverdBytes = 0;
receiverdBytes = data.length+ receiverdBytes;
float prog = (float)[responseData length]/(float)len;
[progress8 setProgress:prog];
}];
as the download progresses, I want to update the progress bar, but using this code, I am not getting a gradual progress, instead it is waiting to complete the download and jumping to the maximum value. How can I make a gradual progress in the value?
Can somebody provide a sample code? For asynchronous method with delegate methods.
Thanks :)
If you don't want to code everything on your own, I would suggest using ASIHTTPRequesst on this task:
http://allseeing-i.com/ASIHTTPRequest/How-to-use
It is very simple to implement and you can do simultaneous, asynchrony downloads. It also provides delegates for all needs, also for progress updates.
I used it in my projects for almost a year now and never regretted it.
CompletionHandler is executed at completion, of course. You have to a delegate for the connection. Use -initWithRequest:delegate: method. You will have to code the NSURLConnectionDelegate methods and the one you need to set progressView value is -connection:didReceiveData:
Here is the doc: https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/URLLoadingSystem/URLLoadingSystem.pdf
I am currently working on an application I need to receive the data in order its very important so instead of going with asynchronous I am using synchronous. However this introduces a very unfortunate side effect, the synchronous request locks up the UI thread.
What I am doing to combat this issue is introduce Multithreading into my app with the use of the life saving "Grand Central Dispatch" services, which seems to be very easy to get my head around so far.
So with all this in mind I am having an issue with what I am doing, Previously I was using asynchronous and everything worked sweet, changing that to synchronous gives me this error
Error Domain=ASIHTTPRequestErrorDomain Code=1 "A connection failure occurred" UserInfo=0x68052a0 {NSUnderlyingError=0x683d250 "The operation couldn’t be completed. Connection refused", NSLocalizedDescription=A connection failure occurred}
Heres my code so far.
- (IBAction)setRequestString:(NSString *)string
{
//Set database address
NSMutableString *databaseURL = [[NSMutableString alloc] initWithString:#"http://192.168.1.1:8778/Data/"]; // iphone development
//PHP file name is being set from the parent view
[databaseURL appendString:string];
//call ASIHTTP delegates (Used to connect to database)
NSURL *url = [NSURL URLWithString:databaseURL];
//Used to Check which ASI cache to use (also used in requestFinished
xmlFileName = [[NSString alloc] initWithFormat:string];
//Set up multithread with GCD
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
//Create If statments here to set up the different caches to be passed down to the next view
if ([string isEqualToString:#"high.xml"]){
//Cache stuff goes in here
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDownloadCache:[ASIDownloadCache sharedCache]];
[request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
[request setCachePolicy:ASIOnlyLoadIfNotCachedCachePolicy];
[request setSecondsToCache:60*60*24*30]; // Cache for 30 days - this will change to cache until DBVersion changes
[request setDelegate:self]; // this calls the delegate function requestFinished
dispatch_sync(queue, ^ {
[request startSynchronous];
});
}else if ([string isEqualToString:#"low.xml"]){
//Cache stuff goes in here
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDownloadCache:[ASIDownloadCache sharedCache]];
[request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
[request setCachePolicy:ASIOnlyLoadIfNotCachedCachePolicy];
[request setSecondsToCache:60*60*24*30]; // Cache for 30 days - this will change to cache until DBVersion changes
[request setDelegate:self]; // this calls the delegate function requestFinished
dispatch_sync(queue, ^ {
[request startSynchronous];
});
}
}
- (void)requestFinished:(ASIHTTPRequest *)request
{
//.... etc
hopefully that gives you a better idea of what im trying to do, I think maybe I am missing something with the way I am declaring my syncronious start.. as in the asihttprequest help file they say to declare it like this
- (IBAction)grabURL:(id)sender
{
NSURL *url = [NSURL URLWithString:#"http://allseeing-i.com"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request startSynchronous];
NSError *error = [request error];
if (!error) {
NSString *response = [request responseString];
}
}
however Im working with data.. so this line
NSString *response = [request responseString];
will not work? dose it need to be NSData.. etc I dunno if someone could help me out that would be great.
You can use nsoperationqueue...
you can create one NSoperationInvoke and add those to NSoperationQueue in order(after reciving data sending another request)...You can add observer to NSOperationQueue to ensure that how many request will process at a time...in your case it will be just one...after receiving the notification in the observer that the synchronous process is completed it will call a selector by performonMainThread for starting another request in the observer itself...
on NSString *response = [request responseString];
issue you can check the request object by [request iskindofClass:[ClassName class]];
or nslog("%#",[request describe]);
it will tell what kind of object request is
Have you considered just adding a serial queue to your code?
dispatch_queue_t queue = dispatch_queue_create("com.myapp", NULL);
You are using a concurrent thread and it's causing multiple operations to occur at the same time. Also, wrap properly your ASIHttpRequest code within the queue blocks.
Give that a try and let us know
I need a good solution for my little issue.
What I have at the moment:
My App works with asyncron https request very well. At the moment the app uploads an JSON object, so far so good. After that I save the object in an sqlite database.
Now I have to change to determine what the received server response code is.
I will get an response code like 000 if the uploaded data was valid, and a code like 151 if not. For that I have to wait for the server response to save the response code in the database as well.
I experimented with NSThread, too. But that didn't work out as well as I expected.
Somebody any suggestions? I mean, it should be one of the most common things ;) I just don't see it.
thx, dominik
I usually use an NSOperationQueue to manage my communication. This lets you use a synchronous request instead of asynchronous, and handle the whole shebang in one method.
Example:
-(void)doIt {
NSInvocationOperation *op = [[[NSInvocationOperation alloc] initWithTarget:self selector:#selector(doIt_) object:nil] autorelease];
[opQueue addOperation:op];
}
-(void)doIt_ {
NSData *data;
NSMutableURLRequest *request;
NSURLResponse *response = nil;
NSError *error = nil;
// Build request to spec
data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:error];
// do something with data
[self performSelectorOnMainThread:#selector(yadda) withObject:yaddayadda waitUntilDone:NO];
}
If you do use the asynchronous loading methods, you have to implement a delegate to catch the response data as it comes down, and do something with it when finished.
I recommend that you take a look at ASIHTTPRequest which is a wrapper for the CFNetwork API. Particularly look into the mechanism it offers for asynchronous HTTP requests, where you can define blocks to be executed once the request has completed or failed and can you can inspect the response data easily. Your code would be something like this:
__block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setRequestMethod:#"POST"];
// add your json object to the request
[request setCompletionBlock:^{
int responseCode = [request responseStatusCode];
NSData *responseData = [request responseData];
// do whatever you want with this info
}];
[request setFailedBlock:^{
NSError *error = [request error];
// handle the error
}];
[request startAsynchronous];
i try to use applicationWillTerminate in my app and i want that in this function i will send data to server,with this:
reqURL = [reqURL stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:reqURL]];
NSURLResponse *resp = nil;
NSError *err = nil;
NSData *response = [NSURLConnection sendSynchronousRequest: theRequest returningResponse: &resp error: &err];
but the problem is that this function didn't call when i close my app.
In iOS 4.x, apps are often moved into the background (in order to be quickly resumed) as opposed to being purged from memory. applicationWillTerminate: is only called when the latter occurs. You probably want applicationDidEnterBackground: which will be called when your app is quit but continues to stick around in the background. You will only have about 5 seconds to do any clean-up so you may also want to look into the beginBackgroundTaskWithExpirationHandler: / endBackgroundTask: methods in case your request is of critical importance and possibly requires more time.
Most likely the application will be going into the background state, not exiting completely. Try putting your code into:
- (void)applicationWillResignActive:(UIApplication *)application;