As I understand methods named *WithContentsOfURL: like [NSData dataWithContentsOfURL:] are synchronous.
So if I want to download from 3 URLs asynchronously using *WithContentsOfURL: methods I have to put them in a GCD dispatch like:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSData *dataOne = [NSData dataWithContentsOfURL:dataOne];
NSData *dataTwo = [NSData dataWithContentsOfURL:dataTwo];
NSData *dataThree = [NSData dataWithContentsOfURL:dataThree];
});
Is NSURLConnection using GCD "behind the scenes"? Would this be (somewhat) equivalent to the below methods in terms of asynchronous download:
NSURLRequest *myRequestOne = [NSURLRequest requestWithURL:[NSURL URLWithString:URLOne] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
NSURLConnection *myConnectionOne = [[NSURLConnection alloc] initWithRequest:myRequestOne delegate:self];
NSURLRequest *myRequestTwo = [NSURLRequest requestWithURL:[NSURL URLWithString:URLTwo] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
NSURLConnection *myConnectionThree = [[NSURLConnection alloc] initWithRequest:myRequestTwo delegate:self];
NSURLRequest *myRequestThree = [NSURLRequest requestWithURL:[NSURL URLWithString:URLThree] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
NSURLConnection *myConnectionThree = [[NSURLConnection alloc] initWithRequest:myRequestThree delegate:self];
Also what would happen if I would put a NSURLConnection inside a dispatch_async ?
They're not really equivalent, since using NSURLConnectionDelegate allows you to react to things like request failure, authentication challenge etc.
The first example you give using GCD would work for valid URLs, but for anything else will result in no data being returned. Do as Eugene suggests and use ASIHTTPRequest - it's much easier.
Just use ASIHTTPRequest, asynchronous requests are implemented there you'll just have to do something like this:
ASIHTTPRequest *myRequestOne = [ASIHTTPRequest requestWithURL:URLOne];
[myRequestOne setCompletionBlock:^ {
// do something with [request responseData];
}];
[myRequestOne startAsynchronous];
Related
As ios documentation says, [webView stopLoading] method should be used in order to stop webview load task.
As far as I see, this methods runs asynchronously, and does NOT stop currently processing load request immediately.
However, I need a method which will force webview to immediately stop ongoing task, because loading part blocks the main thread, which could result in flicks on animations.
So, is there a way to succeed this?
This worked for me.
if (webText && webText.loading){
[webText stopLoading];
}
webText.delegate=nil;
NSURL *url = [NSURL URLWithString:#""];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[webText loadRequest:requestObj];
Don't use the UIWebView to download your html document directly.
Use async download mechanism like ASIHTTPRequest to get your html downloaded by a background thread.
When you get the requestFinished with a content of your html then give it to the UIWebView.
Example from the ASIHTTPRequest's page how to create an asynchronous request:
- (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];
}
Use the responseString to your UIWebView's loadHTMLString method's parameter:
UIWebView *webView = [[UIWebView alloc] init];
[webView loadHTMLString:responseString baseURL:[NSURL URLWithString:#"Your original URL string"]];
The URL is written properly, I tested it in the browser with data and it sends properly, but when I make the request, it returns that it is successful, but it does not actually write the data. Any idea?
- (void)writeAboutMe:(NSString *)about withIcebreaker:(NSString *)icebreaker
{
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
NSString *urlString = [NSString stringWithFormat:#"http://nailorbail.net63.net/submit_about_and_icebreaker.php?username=%#&about=%#&icebreaker=%#",[SignInViewController getUsernameString] ,about,icebreaker];
NSLog(#"%#",urlString);
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:#"GET"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Current-Type"];
NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];
if(conn)
NSLog(#"Connection Successful");
else
NSLog(#"Connection could not be made");
[conn release];
}
It could be an encoding issue. What kinds of characters are in getUsernameString, about, and icebreaker? As Maudicus mentioned, you need to handle special characters in the URL yourself.
Try:
urlString = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]
You have set up an asynchronous connection. Do you implement the NSURLConnection delegate protocol methods? Are any of them being called?
The creation of the connection instance doesn't say anything about it's success.
Check out some tutorials, like this one.
I am using soap webservice.
In that i am calling one webmethod. Here if i call from one part of my code is working fine and calling service successfully and retriving data successfully.
But if i calling same method from another part of code of same class is not responding and not getting any data from service. Why is going like that can any one help me please.
Thanks in advance
In detail.m
-(void) downloadAndParse:(NSMutableURLRequest *)sentReq {
conn = [[NSURLConnection alloc] initWithRequest:sentReq delegate:self];
if (conn) {
webData = [[NSMutableData data] retain];
}
}
-(void)fullBarcodeSearch:(NSString *)code {
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
URLRequest *r = [[URLRequest alloc] init];
NSMutableURLRequest *req = [r fullBarcodeSearch:code];
[r release];
[self downloadAndParse:req];
}
In URLRequest.m
-(NSMutableURLRequest *) addHeaderToSoapXML:(NSString *) soapMsg {
NSURL *url = [NSURL URLWithString:str];
NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url];
NSString *msgLength = [NSString stringWithFormat:#"%d",[soapMsg length]];
[req addValue:#"text/xml; charset=utf-8" forHTTPHeaderField:#"content-type"];
[req addValue:msgLength forHTTPHeaderField:#"Content-Length"];
[req setHTTPMethod:#"POST"];
[req setHTTPBody:[soapMsg dataUsingEncoding:NSUTF8StringEncoding]];
return req;
}
if service not called then i am getting error like this
*oid _WebThreadLockFromAnyThread(bool), 0x6958130: Obtaining the web lock from a thread other than the main thread or the web thread. UIKit should not be called from a secondary thread.*
Please any one help me
Thanks in advance
You need an NSURLConnection to execute the NSURLRequest. Lookup the Apple Docs on the class.
Something like:
[urlConnection sendSynchronousRequest:urlRequest returningResponse: &urlResponse error:&error]
I am trying to write an iPhone app in Objective-C. I need to POST data using NSURLConnection. Every example I can find deals with JSON; I do not need to use JSON. All I need to do is POST the data and get a simple 1 or 0 (succeed or fail) from a PHP script. Nothing more.
I came across this code but I am not sure how to use it or modify it to not use JSON:
- (void)performRequest {
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:#"http://someplace.com/"]];
[request setValue:#"Some Value" forHTTPHeaderField:#"Some-Header"];
[request setHTTPBody:#"{\"add_json\":\"here\"}"];
[request setHTTPMethod:#"POST"];
[NSURLConnection connectionWithRequest:[request autorelease] delegate:self];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
// Fail..
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
// Request performed.
}
Here's how to create an ordinary post.
First create a request of the right type:
NSURL *URL = [NSURL URLWithString:#"http://example.com/somepath"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
request.HTTPMethod = #"POST";
Now format your post data as a URL-encoded string, like this:
NSString *params = #"param1=value1¶m2=value2&etc...";
Remember to encode the individual parameters using percent encoding. You can't entirely rely on the NSString stringByAddingPercentEscapesUsingEncoding method for this (google to find out why) but it's a good start.
Now we add the post data to your request:
NSData *data = [params dataUsingEncoding:NSUTF8StringEncoding];
[request addValue:#"8bit" forHTTPHeaderField:#"Content-Transfer-Encoding"];
[request addValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Content-Type"];
[request addValue:[NSString stringWithFormat:#"%i", [data length]] forHTTPHeaderField:#"Content-Length"];
[request setHTTPBody:data];
And that's it, now just send your request as normal using NSURLConnection (or whatever).
To interpret the response that comes back, see Maudicus's answer.
You can use the following NSURLConnection method if you target ios 2.0 - 4.3 (It seems to be deprecated in ios 5)
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
NSString * string = [[NSString alloc] initWithData:data encoding:
NSASCIIStringEncoding];
if (string.intValue == 1) {
} else {
}
}
I've a very similar situation to whitebreadb. I'm not disagreeing with the answers submitted and accepted but would like to post my own as the code provided here didn't work for me (my PHP script reported the submitted parameter as a zero-length string) but I did find this question that helped.
I used this to perform a posting to my PHP script:
NSURL *URL = [NSURL URLWithString:[NSString stringWithFormat:#"http://www.myphpscriptlocation.net/index.php?userID=%#",self.userID_field.stringValue]];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
request.HTTPMethod = #"POST";
NSURLConnection *c = [NSURLConnection connectionWithRequest:request delegate:self];
I'm developing an iOS app which gets its data from a json feed of my server. Parsing the string is no problem... However, I am having trouble downloading the string asynchronously and then caching it. I found SDURLCache but do not know how to implement it. What is the best way to do this.
You could download the file to disk (synchronously):
NSURL * url = [NSURL URLWithString:#"www.yourprovider.com/your.json";
NSData *file = [NSData dataWithContentsOfURL:url];
[file writeToFile:<your file path> atomically:YES];
For asynchronous operations, instead, you should use NSURlConnection. After opening the connection,
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:<your NSURL>];
[request setHTTPMethod:#"GET"];
NSURLConnection *conn = [NSURLConnection connectionWithRequest:request delegate:self];
[conn start];
you receive data in this call back:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)_data {
//here you could write to a NSFileHandle ivar:
if (file) {
[file seekToEndOfFile];
} [file writeData:_data];
}