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];
}
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"]];
I'm looking to create a simple iOS app that displays the current water level of a local lake. The water level is updated daily on a specific URL. Is it possible to pull content from a webpage using objective c?
Sure. Check out the URL Loading System Programming Guide. From that link:
The URL loading system provides support for accessing resources using the following protocols:
File Transfer Protocol (ftp://)
Hypertext Transfer Protocol (http://)
Secure 128-bit Hypertext Transfer Protocol (https://)
Local file URLs (file:///)
Absolutely! Use the NSURLConnection object. Use something like the function below, just pass an empty string for 'data' and then parse the HTML returned to find the value you're looking for.
-(void)sendData:(NSString*)data toServer:(NSString*)url{
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
NSData *postData = [data dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%d",[postData length]];
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:url]];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Current-Type"];
[request setHTTPBody:postData];
NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];
if(conn){
//Connection successful
}
else{
//Connection Failed
}
[conn release];
}
Easier way yet using threading:
- (void)viewDidLoad
{
[self contentsOfWebPage:[NSURL URLWithString:#"http://google.com"] callback:^(NSString *contents) {
NSLog(#"Contents of webpage => %#", contents);
}];
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void) contentsOfWebPage:(NSURL *) _url callback:(void (^) (NSString *contents)) _callback {
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);
dispatch_async(queue, ^{
NSData *data = [NSData dataWithContentsOfURL:_url];
dispatch_sync(dispatch_get_main_queue(), ^{
_callback([[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
});
});
}
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 have a php file on my server that takes two argument and register my users.Can any one tell me the easiest way to send request to that gile and get response?
**My php file returns integer value like 1 for successful registration.2 For User exists.
You can use the NSURLConnection with NSMutableURLRequest or NSURLRequest
The class that you make the request in should implement this code.
-(void)yourMethod
{
// assume your append is a string of format ?key1=value1&key2=value2
NSString * urlString = [NSString stringWithFormat:#"https://www.stackoverflow.com/myPhpFile.php%#", append];
urlRequest = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:urlString]];
urlConnection = [NSURLConnection connectionWithRequest:urlRequest delegate:self];
[urlRequest release];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
NSString * string = [[NSString alloc] initWithData:data encoding:
NSASCIIStringEncoding];
// check string for successful registration
[string release];
}
You don't need to use https if your site does not have an SSL certificate.
I am writing a program in Objective-C and I need to make web requests to web server, but asynchronously and I am fairly new on mac, I am very good at windows technologies, but I need to know that if I use NSOperation (introduced in 10.5, i am assuming that it will not run in 10.4 MAC?), or if it was implemented such that it utilizes system threading which will be available on 10.4?
Or I should create a new thread and create a new runloop, also how to use cookies etc, if anyone can give me one small example, that will be of great help. I want this sample to run on mac 10.4 too if possible.
There's a good example of using NSURLRequest and NSHTTPCookies to do a full web application example of logging into a website, storing the SessionID cookie and resubmitting it in future requests.
NSURLConnection, NSHTTPCookie
By logix812:
NSHTTPURLResponse * response;
NSError * error;
NSMutableURLRequest * request;
request = [[[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:#"http://temp/gomh/authenticate.py?setCookie=1"]
cachePolicy:NSURLRequestReloadIgnoringCacheData
timeoutInterval:60] autorelease];
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSLog(#"RESPONSE HEADERS: \n%#", [response allHeaderFields]);
// If you want to get all of the cookies:
NSArray * all = [NSHTTPCookie cookiesWithResponseHeaderFields:[response allHeaderFields] forURL:[NSURL URLWithString:#"http://temp"]];
NSLog(#"How many Cookies: %d", all.count);
// Store the cookies:
// NSHTTPCookieStorage is a Singleton.
[[NSHTTPCookieStorage sharedHTTPCookieStorage] setCookies:all forURL:[NSURL URLWithString:#"http://temp"] mainDocumentURL:nil];
// Now we can print all of the cookies we have:
for (NSHTTPCookie *cookie in all)
NSLog(#"Name: %# : Value: %#, Expires: %#", cookie.name, cookie.value, cookie.expiresDate);
// Now lets go back the other way. We want the server to know we have some cookies available:
// this availableCookies array is going to be the same as the 'all' array above. We could
// have just used the 'all' array, but this shows you how to get the cookies back from the singleton.
NSArray * availableCookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:[NSURL URLWithString:#"http://temp"]];
NSDictionary * headers = [NSHTTPCookie requestHeaderFieldsWithCookies:availableCookies];
// we are just recycling the original request
[request setAllHTTPHeaderFields:headers];
request.URL = [NSURL URLWithString:#"http://temp/gomh/authenticate.py"];
error = nil;
response = nil;
NSData * data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSLog(#"The server saw:\n%#", [[[NSString alloc] initWithData:data encoding: NSASCIIStringEncoding] autorelease]);
For asynchronous requests, you need to use NSURLConnection.
For cookies, see NSHTTPCookie and NSHTTPCookieStorage.
UPDATE:
The code below is real, working code from one of my applications. responseData is defined as NSMutableData* in the class interface.
- (void)load {
NSURL *myURL = [NSURL URLWithString:#"http://stackoverflow.com/"];
NSURLRequest *request = [NSURLRequest requestWithURL:myURL
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:60];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
responseData = [[NSMutableData alloc] init];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responseData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
[responseData release];
[connection release];
// Show error message
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
// Use responseData
[responseData release];
[connection release];
}
I am able to fetch cookie in such way:
NSArray* arr = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:[NSURL URLWithString: #"http://google.com" ]];
This one works fine for asynchronous request as well.