I have a loop of about 2000+ items I need to go through:
for (NSDictionary* dict in array) {
NSString *fileName = [NSString stringWithFormat:#"%#/%#_lg.jpg?t=",manufacturerID, [[dict valueForKey:#"ItemID"] stringByReplacingOccurrencesOfString:#" " withString:#"%20"]];
NSString *savePath = [documentsPath stringByAppendingPathComponent:fileName];
NSURL *url = [NSURL URLWithString: [[NSString stringWithFormat:kProductImagesURL, fileName]stringByAppendingString:lastImagesSyncDate]];
dispatch_queue_t aQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);
dispatch_async(aQueue, ^{
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request startSynchronous];
NSError *error = [request error];
if (!error) {
int statusCode = [request responseStatusCode];
if (statusCode==200) {
NSData *responseData = [request responseData];
[responseData writeToFile:[savePath stringByReplacingOccurrencesOfString:#"%20" withString:#" "] atomically:YES];
}
}
});
}
This works great and my main thread is not blocked but my memory goes through the roof - how do I get it to be released? Once the queue is empty it drops but I need it to clear out as it is going along.
Although you are running the code in the background you are running all of the code in the background at the same time. As fast you are able to loop through the array you are creating a new ASIHttpRequest that will be trying to download and save data at the same time. You may want to move your loop inside of the dispatch_async, or use an NSOperation that does the same thing but limit the max concurrent operations on the NSOperationQueue. If you move the loop inside of dispatch_async to do one at a time remember to create an NSAutoreleasePool locally and drain it periodically.
Instead of getting an autoreleased ASIHTTPRequest , try to alloc ,init , release one.
Haven't tried it , but think about alternating async and sync calls (to the same thread, not the main one) , like having 20 async requests followed by one sync.. this trick could help.
Related
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 am trying to use the ASIDownloadCache from the ASIHTTPRequest library. I think I have it almost set up but the data I am printing to the log is a bunch of numbers.. I think it might be a formatting problem.. but I would like to run it past someone with more experience first to make sure I'm doing it correctly and then to hopefully help me fix the issue.
The code belows shows you how I am setting up my cache, I am using this view for several data sets, hence the need to use an if statement so that I am only setting up the cache on specific data.
- (IBAction)setRequestString:(NSString *)string
{
//Set database address
NSMutableString *databaseURL = [[NSMutableString alloc] initWithString:#"http://***.***.***.***:8888/codeData/"]; // 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];
checkDataSet = [[NSString alloc] initWithFormat:string]; //Loads ICMfg.xml into checkDataSet for setting up cache
//Create If statments here
if ([checkDataSet isEqualToString:#"ICMfg.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
[request setDelegate:self]; // A delegate must be specified
[request startSynchronous];
//[request setDidFinishSelector:#selector(requestFinished:)]; // And an appropriate
}
else
{
//this else statments lets all of the other datasets come through here
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];
[request setDelegate:self];
[request startAsynchronous];
}
}
From here, when [checkDataSet isEqualToString:#"ICMfg.xml"] is true it will set the cache parameters and then calls the following method where I get everything ready to parse my information
- (void)requestFinished:(ASIHTTPRequest *)request
{
if ([checkDataSet isEqualToString:#"ICMfg.xml"]) {
BOOL success = [request didUseCachedResponse];
NSLog(#"------------>>>>>>> Success is %#\n", (success ? #"YES" : #"NO"));
responseString = [request responseString];
capturedResponseData = [responseString dataUsingEncoding:NSUTF8StringEncoding];
NSLog(#"%#", capturedResponseData); //this prints out the weird data.
[self startTheParsingProcess:capturedResponseData];
}
else
{
responseString = [request responseString]; //Pass requested text from server over to NSString
capturedResponseData = [responseString dataUsingEncoding:NSUTF8StringEncoding];
[self startTheParsingProcess:capturedResponseData];
}
}
From here, I check my nslog to see the result of that NSlog and it spits out a bunch of numbers, below is a small section of the output. The next step for me is to check to see if anything is actually being parsed.. and also to see if the cache is working or not.. then I need to figure out hopefully with your help how to format the data correctly if thats my main problem..
also I would like to ask how to get this working asynchronously as currently I can only get it to work synchonosly.
2011-11-09 09:29:55.216 code[3968:207] ------------>>>>>>> Success is YES
2011-11-09 09:29:55.239 code[3968:207] <3c3f786d 6c207665 7273696f 6e3d2231 2e302220 656e636f 64696e67 3d225554 462d3822 3f3e0d0a 3c494345 6e673e3c 52657375 6c742044 42566572 73696f6e 3d223132 33223e3c 5461626c 65733e3c 5461626c 65205461 626c654e 616d653d 2249434d 6667223e 3c526f77 733e3c52 6f77204d 414e5546 41435455 52455249 443d2237 30362220 4d414e55 46414354 55524552 3d22412d 445a4722 2049534c 4f434b4d 414e5546 41435455 5245523d 22462220 49535645 4849434c 453d2246 223e3c2f 526f773e 3c526f77 204d414e 55464143 54555245 5249443d 22333138 22204d41 4e554641 43545552 45523d22 412e522e 452e2220 49534c4f 434b4d41 4e554641 43545552 45523d22 46222049
any help would be greatly appreciated.
I don't see anything that immediately sticks out in your code as wrong.
The NSLog() is printing an NSData object, which is binary data so the hexadecimal numbers you are seeing are the representations of the bytes which is exactly what you would expect.
The NSData Class Reference:
description
Returns an NSString object that contains a hexadecimal
representation of the receiver’s contents.
(NSString *)description
Return Value
An NSString object that contains a hexadecimal representation of the receiver’s contents in
NSData property list format.
If you want to print out the string representation of this data, use:
NSString *capturedResponseString = [NSString stringWithUTF8String:[capturedResponseData bytes]];
I m using sendSynchronousRequest to get the data from the server. I know that synchronous will wait until the data received for that request.
But the problem comes when user by mistake enters some non-existing url and than tries to get response. In this case, if user goes in to background and than comes into foreground it shows only black screen. It only shows status bar. Also its not showing any background application. I have to press Home button to come out of my application.
On simulator, After 1+ minute it shows me the message that "Request time out" (No crash).
On Device, within 1 min application get crashes.
Any suggestion. Any Help. This is really a serious issue in my app.
Thanks.
Just like Julien said, the watchdog is killing your app. To answer some questions:
why does this happen only on the simulator?
Because when you're debugging the watchdog leaves your app alone, it can take time.
why does this happen only when the user enters a wrong url?
Because of the system timeout, the system will keep trying for 60 secs if it can't find a server.
so the problem is synchronous vs asynchronous?
No, the problem is the thread, you can do the same operation in a background thread, just don't do it on the main thread and the watchdog will leave you alone.
why is the screen black when the app comes up?
Remember, you are making blocking stuff on the main thread, the thread that draws...
Hope that was all. Let me know if I missed something.
Why not setting a timeout for your connection?
NSString *urlString = TEST_CONNECTION;
NSError *error = nil;
NSHTTPURLResponse *response = nil;
NSURLRequest *request = [NSURLRequest
requestWithURL:[NSURL URLWithString:urlString]
cachePolicy:NSURLRequestReloadIgnoringCacheData
timeoutInterval:5.0];
NSData *conn = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
This should release the synchronous waiting after a number of seconds, which should solve your problem without going with an asynchronous call (which sometimes isn't the proper solution)
I know this works properly because this is how I check if I am connected to a certain VPN (where reachability flags totally fail).
you should take a look to this article: https://developer.apple.com/library/ios/#qa/qa1693/_index.html
iOs contains a watchdog, if your application is blocked to much time on an operation on the main thread, this one will be killed. (for more details about Watchdog: http://en.wikipedia.org/wiki/Watchdog_timer)
So if you want to download something, don't download it on the main thread.
RELATE
UIImage *image = [self.imgCache objectForKey:urlString];
if(!image){
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:urlString] cachePolicy:NSURLRequestReturnCacheDataElseLoad timeoutInterval:60.0];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSURLResponse *response = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];
NSLog(#"%#",response);
UIImage *img = [UIImage imageWithData:data];
//
if(img)
{
dispatch_sync(dispatch_get_main_queue(), ^{
[self.imgCache setObject:img forKey:urlString];
completionBlock(img);
});
}
});
}
else{
completionBlock(image);
}
use ASIHttpRequest class instead of NSURLConnection , its nothing but wrapper around NSURLConnection and has very simple callbacks , you can also set time to complete a request. Please go through this link for more info http://allseeing-i.com/ASIHTTPRequest/
I think you first have to test user data whether it is correct or not and than only if it is correct, sends the request otherwise prompt user that "please enter correct data"...
or
when your parsing of data in response failed. You can also make protocol delegate method i.e FinishWithError so that you come up with your last UI.
Try this one:
#import "ASIHTTPRequest.h"
//In a method
[self performSelectorInBackground:#selector(DownLoadImageInBackground:) withObject:imgUrlArr];
-(void) DownLoadImageInBackground:(NSArray *)imgUrlArr1
{
NSURL * url = [Image URL];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[request startAsynchronous];
}
-(void)requestFailed:(ASIHTTPRequest *)request
{
NSLog(#"URL Fail : %#",request.url);
NSError *error = [request error];
// you can give here alert too..
}
-(void)requestFinished:(ASIHTTPRequest *)request
{
NSData *responseData = [request responseData];
UIImage *imgInBackground = [[UIImage alloc]
initWithData:responseData];
[imageView setImage: imgInBackground];
}
This might help you: I am also loading a number of images at one time, so images that have no proper data show a black screen. To avoid this, try to resize your imageview.
You could check the reachability of the URL before starting the request.
Apple has Reachability Methods to do so. But its easier to use a wrapper. E.g. ASIReachability.
I think the application crashing because you does not get any data when user enters wrong URL and you are using this 'returned' nil NSData to do stuffs.
I think this will fix your problem
NSData *data=[NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:&error];
if(data!=nil){
///
} else {
NSLog(#"NO DATA");
}
I'm using ASIHTTPRequest in asynchronous mode in a function called from my viewDidLoad()
NSURL *url = [NSURL URLWithString:#"http://somewebsite.com/data.txt"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[request startAsynchronous];
This is my requestFinished() where I do some text replacement and populate an NSArray with the data I've received from the website. It's just text, one data item per line.
The NSArray (and alloc / init) in viedDidLoad().
- (void)requestFinished:(ASIHTTPRequest *)request
{
NSString *sTemp = [request responseString];
sTemp = [sTemp stringByReplacingOccurrencesOfString:#"\n" withString:#","];
arrayTidalData = [sTemp componentsSeparatedByString:#","];
NSLog(#"Loaded %d items into the array",[arrayTidalData count]);
[tableTideTimes reloadData];
}
NSLog reports 127 data items.
Now, I use the NSArray data to populate a UITableView.
But, in cellForRowAtIndexPath() when I attempt to access the NSArray (arrayTidalData), for instance by doing a count, I get the following:
TideTimes[14696:b303] * -[__NSArrayM count]: message sent to deallocated instance 0x4e6c6a0
(I turned on NSZOMBIEEnabled = YES to get this data)
It seems the NSArray has been deallocated before I can use it. I also tried populating an NSString with the data in requestFinish() but got the same result.
Am I missing something really simple or am I doing something terribly wrong?
(It's my first time with ASIHTTPRequest)
Replace
arrayTidalData = [sTemp componentsSeparatedByString:#","];
with
arrayTidalData = [[sTemp componentsSeparatedByString:#","] retain];
It is because componentsSeparatedByString: returns autoreleased object. So it is released after method requestFinished: ends working.
And don't forget to release at the end of work (for example, dealloc).