I'm using initWithContentsOfURL of NSData to load an image from a url. However, I don't know the size of the image beforehand, and I would like to the connection to stop or fail if the response exceeds a certain size.
Is there a way to do this in iPhone 3.0?
Thanks in advance.
You can't do it directly via NSData however NSURLConnection would support such a thing by loading the image asynchronously and using connection:didReceiveData: to check how much data you have received. If you go over your limit just send the cancel message to NSURLConnection to stop the request.
Simple example: (receivedData is defined in the header as NSMutableData)
#implementation TestConnection
- (id)init {
[self loadURL:[NSURL URLWithString:#"http://stackoverflow.com/content/img/so/logo.png"]];
return self;
}
- (BOOL)loadURL:(NSURL *)inURL {
NSURLRequest *request = [NSURLRequest requestWithURL:inURL];
NSURLConnection *conn = [NSURLConnection connectionWithRequest:request delegate:self];
if (conn) {
receivedData = [[NSMutableData data] retain];
} else {
return FALSE;
}
return TRUE;
}
- (void)connection:(NSURLConnection *)conn didReceiveResponse:(NSURLResponse *)response {
[receivedData setLength:0];
}
- (void)connection:(NSURLConnection *)conn didReceiveData:(NSData *)data {
[receivedData appendData:data];
if ([receivedData length] > 5120) { //5KB
[conn cancel];
}
}
- (void)connectionDidFinishLoading:(NSURLConnection *)conn {
// do something with the data
NSLog(#"Succeeded! Received %d bytes of data", [receivedData length]);
[receivedData release];
}
#end
Related
I have an application and I used to get my json data with dataWithContentsOfURL.
But because I need to get it an asynchrone fashion.
Now that I use NSURLConnection to handle this I don't receive any useful data all I get is statuscode 200 in the didReceiveResponse method but didReceiveData is never called.
And at connectionDidFinishDownloading destinationURL returns null.
I have no idea wat couses this problem and I would really appreciate some help.
the delegate
#import "NetWorkToGuiDelegate.h"
#implementation NetWorkToGuiDelegate
#synthesize data;
#synthesize caller;
- (id) init: (SEL) pointer :(NSObject *) c;
{
doWhenDone = pointer;
self.caller = c;
data = [[NSMutableData alloc]init];
return self;
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *responseText = [[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding];
NSLog(#"%#",responseText);
}
- (void)connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *)destinationURL
{
NSLog(#"post download finished");
data = [NSData dataWithContentsOfURL:destinationURL];
NSLog(#"data: %#",data);
NSLog(#"URLconnection %#", connection.currentRequest);
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
[caller performSelector:doWhenDone withObject:data];
#pragma clang diagnostic pop
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[self.data setLength:0];
NSHTTPURLResponse *resp= (NSHTTPURLResponsae *) response;
NSLog(#"got responce with status %d",[resp statusCode]);
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)d
{
NSLog(#"data recieved %#",d);
[self.data appendData:d];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
[[[UIAlertView alloc] initWithTitle:NSLocalizedString(#"Error", #"")
message:[error localizedDescription]
delegate:nil
cancelButtonTitle:NSLocalizedString(#"OK", #"")
otherButtonTitles:nil] show];
NSLog(#"failed");
}
// Handle basic authentication challenge if needed
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
NSString *username = #"username";
NSString *password = #"password";
NSURLCredential *credential = [NSURLCredential credentialWithUser:username
password:password
persistence:NSURLCredentialPersistenceForSession];
[[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
}
#end
the call
NetWorkToGuiDelegate *nwgd = [[NetWorkToGuiDelegate alloc] init:#selector(login:) :self];
NSString *stringURL = [NSString stringWithFormat:#"%#%#%#%#", dk.baseURL, #"menu?code=",dk.loginCode,#"&v=1"];
NSURL *url = [NSURL URLWithString:stringURL];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
NSURLConnection *urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:nwgd];
[urlConnection start];
I'll just add that the call happens on the main thread
Actually there is a lot of points to make the answer of this question and there are so many questions on SO itself
Go through this nice post
And a must Read doc from apple itself.(contains code samples and explanations)
Hope this will solve the problems for you.
EDIT
-(void)startAConnection
{
// Create the request.
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.apple.com/"]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
// create the connection with the request
// and start loading the data
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest 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.
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
// This method is called when the server has determined that it
// has enough information to create the NSURLResponse.
// It can be called multiple times, for example in the case of a
// redirect, so each time we reset the data.
// receivedData is an instance variable declared elsewhere.
[receivedData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
[receivedData appendData:data];
}
- (void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error
{
// inform the user
NSLog(#"Connection failed! Error - %# %#",
[error localizedDescription],
[[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"Succeeded! Received %d bytes of data",[receivedData length]);
}
Call startAConnection to start the process
NOTE: Don't forget <NSURLConnectionDelegate> in the .h
I have looked at NSURLConnectionDelegate connection:didReceiveData not working already, but there didn't seem to be any good result from that, so I am curious why I am not able to get any data.
I put in breakpoints in didReceiveResponse and didReceiveData.
It does print out "connection succeeded", so I know that the connection is started.
I am using ARC for memory management.
- (void)load {
request = [NSMutableURLRequest requestWithURL:myURL
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:60];
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (conn) {
[conn start];
NSLog(#"connection succeeded, %s", [myURL description]);
responseData = [NSMutableData data];
} else {
NSLog(#"connection failed");
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
responseData = [[NSMutableData alloc] init];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responseData appendData:data];
}
UPDATE:
To see how I test this look at Asynchronous unit test not being called by SenTestCase.
I did implement the two methods mentioned by jonkroll, in his answer, I just didn't show them, but, they also aren't being called.
I had added [conn start] only because it wasn't working, and I was hoping that may solve it, but no such luck.
When you declare your connection like this:
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
You are creating a local pointer. When your method completes, since it was the last strong reference to the NSURLConnection, ARC releases it. You need to use a strong ivar (and/or) property to hold a strong reference to the NSURLConnection you create.
Edit
Here is basic sample of code that I tested in a sample project. Give it a run. Verbose logging helps.
#implementation <#Your class here#> {
// With ARC ivars are strong by default
NSMutableData *_downloadedData;
NSURLConnection *_connection;
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
NSHTTPURLResponse *realResponse = (NSHTTPURLResponse *)response;
if (realResponse.statusCode == 200){
// Really any 2** but for example
_downloadedData = [[NSMutableData alloc] init];
NSLog(#"Good response");
} else {
NSLog(#"Bad response = %i",realResponse.statusCode);
}
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
if (connection == _connection){
[_downloadedData appendData:data];
NSLog(#"Getting data...");
}
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
if (connection == _connection){
_connection = nil;
NSLog(#"We're done, inform the UI or the delegates");
}
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
_connection = nil;
NSLog(#"Oh no! Error:%#",error.localizedDescription);
}
- (void)load {
NSURL *url = [NSURL URLWithString:#"http://www.google.com/"];
NSURLRequest *request = [NSMutableURLRequest requestWithURL:url
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:60];
// Assign strong pointer to new connection
_connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
NSLog(#"Connection was initialized? = %#",(!!_connection)?#"YES":#"NO");
}
#end
The NSURLConnection method initWithRequest starts an asynchronous request for data from a url. Because the request is done asynchronously you can't expect to work with the response in the same method in which the request is invoked. Instead you need to do so in the NSURLConnection's delegate callback methods. You have already implemented didReceiveResponse: and didReceiveData:, but there are a couple others that will be useful to you.
If you want to look at the contents of the response you should do so in connectionDidFinishLoading:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// response is complete, do something with the data
NSLog(#"%#", responseData);
}
The fact that your code prints out "connection succeeded" doesn't really mean that the request was successful, only that the NSURLConnection object was created successfully. To test whether there was a problem with the connection you can implement the delegate method connection:didFailWithError:
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(#"Connection failed! Error - %# %#",
[error localizedDescription],
[[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}
Also there is no need to call [conn start]. The request will be started automatically when you call initWithRequest:
I suggest reading Apple's documentation on Using NSURLConnection for more details.
I have an iOS action - (void)download; - which I have running at the launch of my iOS application.
However, I need another - (void)showData;- which displays data on a UIMapView to wait until all the data has been downloaded through - (void)download - before it begins. Just wondering if anyone knows a way to do that?
Thanks.
First send - (void)download; request and put a progress hud to the ui so user will know that you are downloading data, once you are done with download dismiss progress hud and run your - (void)showData; method
- (void)download{
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (connection) {
receivedData = [[NSMutableData data] retain];
//display loading hud here
} else {
// oh noes!
}
}
- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
[receivedData setLength:0];
}
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[receivedData appendData:data];
int kb = [receivedData length] / 1024;
//dismiss hud here
[self showData];
}
Me again! I am using NSURL to get a file then parse it. I have been looking for a couple of hours now on a progressbar i am trying to implement in my app. I know I first need to get the file size, then keep updating how much data i've downloaded as I continue to pull. I have seen the example using "ASIHTTPRequest" but is there a way to do it with what I already have?
Here is where I start the download.
-(void)parseNewData {
//start network activity spinner and release controller when done
parserDone = NO;
[root downloadIcon];
//create pool to avoid memory leak
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
// get the XML path and start parsing
NSURL *pathURL = [NSURL URLWithString:#"http://www.mysite.com/myfile.xml"];
NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:pathURL];
[parser setDelegate:self];
[parser parse];
//drain pool
[pool drain];
[pool release];
}
Can someone point me in the right direction on how to get file size, then how to update how much I've downloaded. Thanks in advance!
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[webData setLength: 0];
CGFloat size = [[NSString stringWithFormat:#"%lli",[response expectedContentLength]] floatValue];
NSLog(#"Size : %f",size);
}
Above code will give you total size
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[webData appendData:data];
totalDownloadedData += [data length]; // global integer
NSLog(#"Status : %d/%f",totalDownloadedData,size);
}
Above code will show you current status of downloading
You need to use NSURLConnection if you want to get the file size and the progress. You get delegate methods which you can use to monitor progress. The didSendBodyData: delegate method tells you how much data there is in bytes. The connectionDidFinishLoading is where you uget receivedData to use in your NSXMLParser code.
NSURLRequest *theRequest = [NSURLRequest requestWithURL:URL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0];
NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection) {
receivedData = [[NSMutableData data] retain];
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
// This method is called when the server has determined that it
// has enough information to create the NSURLResponse.
// It can be called multiple times, for example in the case of a
// redirect, so each time we reset the data.
// receivedData is an instance variable declared elsewhere.
[receivedData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
// release the connection, and the data object
// inform the user
NSLog(#"Connection failed! Error - %# %#",
[error localizedDescription],
[[error userInfo] objectForKey:NSErrorFailingURLStringKey]);
[connection release];
// receivedData is declared as a method instance elsewhere
[receivedData release];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
[receivedData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite{
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
So here's my issue:
I followed the NSURLConnection tutorial in the iPhone Developer Documentation almost to the T, and it only kinda works.
Here's where it all goes wrong:
The object seems to be created correctly and delegates to connectionDidFinishLoading, but with any URL I try to load the response data always ends up only being 0 bytes. I am running in the simulator if that makes any difference.
Here's my relevant code:
- (void)viewDidLoad {
[super viewDidLoad];
self.title = #"WVFS Player";
//create a request
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://wvfs.josh-kaplan.com/nowPlaying.php"]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
// create a connection
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if(theConnection) {
// create the datum
responseData=[[NSMutableData data] retain];
} else {
// code this later
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[responseData setLength:0];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// make it work
NSLog(#"Succeeded! Received %d bytes of data:",[responseData length]);
// release it
[connection release];
[responseData release];
}
And here's my log output:
[Session started at 2010-03-14 09:01:09 -0400.]
2010-03-14 09:01:14.784 WVFS[19571:207] Succeeded! Received 0 bytes of data:
Any ideas?
You forgot to implement connection:didReceiveData:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responseData appendData:data];
}