I have downloaded a json file (data.json) using NSURLSession. I am trying to access this file from a local html file (main project folder) myfile.html which is displayed via UIWebView. From NSLog I have identified the temp file location is here:
file:///Users/administrator/Library/Developer/CoreSimulator/Devices/166B438D-4F67-448C-B0E5-B32438DA3BF9/data/Containers/Data/Application/FCA61482-BC5D-4804-91F8-891EAB4DB145/tmp/CFNetworkDownload_g6961Q.tmp
My question is how should I access this temp file from the local 'top level' html file, using a relative path?
More generally therefore - how does one access the iOS application file structure from such a top level (relative to the project) html file?
Some background info:
When I manually copy data.json to XCode and access it from myfile.html using the relative path 'data.json' it works.
The download code is:
NSURL *URL = [NSURL URLWithString:#"http://myurl.com/data.json"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];
NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithRequest:request completionHandler:
^(NSURL *location, NSURLResponse *response, NSError *error) {
}
The reason I am doing this with NSURLSession is that I can't do it with Javascript in the html file since it is a cross domain request.
EDIT: Thanks for the helpful answers about adding HTML as a string into the UIWebView. I can see that trying to reference a temp file from the local HTML file is a bit unwieldly and may run counter to Apple's preference of not exposing filepaths - but I am still interested in a definitive answer on whether it can be done.
Perhaps you could inject the JSONData into the web page once it has finished loading within the web view. Something like this (I have not tested it):
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
NSError *error = nil;
NSURL *URL = [NSURL URLWithString:#"http://myurl.com/data.json"];
NSString *result = [NSString stringWithContentsOfURL:URL
encoding:NSUTF8StringEncoding error:&error];
if (!error && result.length > 0)
{
[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:#"var jsonData = \"%#\"", result]];
}
else
{
NSLog(#"Oops: %#", error);
}
}
I don't think you can either. Instead of loading your resource HTML as-is, use it as a "template" and put a "placeholder" string where you need the link to your temp file.
Then, load your HTML into a (mutable) string, replace the placeholder for the actual path to the file and pass this modified HTML string to your web view.
Related
I am currently trying to access a webpage where the user can login using their credentials, after entering their user and password - if correct it will redirect to a new url. This new url loads a webpage with a single string which I intend to use.
However, how am I able to check the contents of the redirected url? At the moment I am only able to check the Response/Data/Contents of the initial page loaded by the following method;
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
casSession = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
NSString *urlAddress = #"https://originalurl.com";
NSURL *httpUrl = [NSURL URLWithString:urlAddress];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:httpUrl];
[loginPage loadRequest:requestObj];
NSURLSessionDataTask *redirect = [casSession dataTaskWithURL:httpUrl completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSString *newURL = [NSString stringWithFormat: #"%#", response.URL];
if ([newURL containsString:#"ticket=ST"]) {
NSString * registrationID = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"REGISTRATION: %#", registrationID);
if (registrationID != nil) {
dispatch_async(dispatch_get_main_queue(), ^{
loginPage.hidden = YES;
});
}
} else {
NSLog(#"No ticket recieved");
}
}];
[redirect resume];
I'm not sure which delegate to use, in order to actively check every time a redirection happens and then obtain the contents of the new url?
Thanks.
You’re looking at this the wrong way. You should query the user for the login info directly and insert that into a single NSURLDataTask. Then the data task should query the server with the login info, and return some data.
This all happens with APIs (in a broad manner of speaking) where you will not present HTML contents to the user, but instead some sort of encoded data that is returned.
So for example, once you have a task defined from a URL or URLRequest, and you begin the task, you then use the completion handler to verify the returned data and/or error. If here, you may decode the returned data as a NSString, and then convert the JSON to objects, such as a user’s profile’s data (name, age, email, ...)
I did not go into detail in this answer because it is a very very broad topic, with many use cases. Look up some tutorials on NSURLDataTasks or consuming APIs from Swift and/or Objective-C.
I'm trying to modify a behavior of a webpage within my iOS app and make the in-page media player play a file from the local caches folder instead of fetching it from a web server.
Below is my code that replaces the http:// video path with a local file path. The code does not work, giving me "Resource Temporary not available. Please try again" error message popup. Is it possible to have a web-based media player play file from a local disk using file URL?
I tried substituting these for the instanceURL, but they don't seem to work.
[fileURL path]
[fileURL absolutePath]
I'm intercepting the request for the file and am parsing it to find out that the page is asking for a video file:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
// An NSURLConnection delegate callback. We pass this on to the client.
{
NSDictionary* decisionDictionary = [[RequestListener sharedInstance] shouldContinue:connection processRequestData:data];
BOOL shouldContinue = [decisionDictionary[#"shouldContinue"] boolValue];
if(shouldContinue == NO)
{
return;
}else
{
NSData* d = data;
//substitute fake data
if(decisionDictionary[#"data"])
{
d = decisionDictionary[#"data"];
}
[[self client] URLProtocol:self didLoadData:d];
}
}
Within my shouldContinue method, I check if the video is present locally and modify the response data to create a path to a local video.
NSString* path = [VideoDownloader localVideoPathForVideoID:videoID];
NSURL* fileURL = [NSURL fileURLWithPath:path];
DLog(#"url:%#",[fileURL absoluteString]);
NSString* replacement = [NSString stringWithFormat:#"\"instanceUrl\":\"%#\"",[[fileURL absoluteURL] absoluteString]];
DLog(#"replacement:%#",replacement);
NSString* forgedResponse = [parts componentsJoinedByString:#","];
NSData* forgedData = [forgedResponse dataUsingEncoding:NSUTF8StringEncoding];
return #{#"shouldContinue":#(YES),#"data":forgedData};
Have a look at NSURLProtocol. You can intercept http requests before they are sent to a host to decide what to do about it: Continue to server, redirect to local cache.
There's a decent tutorial by our beloved Ray Wenderlich.
Apple has a programming guide as well.
In my app I load some static JSON string from some server.
Every now and then the JSON file is updated and then I want the app to reload the data.
Now, that I updated the file on the server the app does not reflect the change. If I take the URL to that file from the app's code and copy it into a browser and fetch the file there, I clearly see the updates. But when I run the app and log the json string to the debug console, then I clearly see an outdated version of the file's content.
Is there any caching involved? Can I force the iOS to actually reload it?
This is how I load it now:
NSURL * url = [NSURL URLWithString:[DOWNLOAD_URL stringByAppendingString:DOWNLOAD_FILE]];
NSError * error;
NSData *jsonData = [NSData dataWithContentsOfURL:url options:NSDataReadingUncached error:&error];
NSLog(#"JSON: %#", [NSString stringWithUTF8String:[jsonData bytes]]);
The option NSDataReadingUncached should prevent the system from caching the data.
PS: When I run the app on a different device, then it receives the current data. But when I again let it run on the original device - on which I observe this behaviour - then the data "received" is still outdated. So it really looks like some cashing issue to me.
Here is an idea. Try calling
[[NSURLCache sharedURLCache] removeAllCachedResponses];
For more granular control on cashing use NSURLConnection or NSURLSession.
I did try Mundi's suggestion, to try clearing the cache, but this didn't make any difference in my iPhone app.
So, I tried a trick which I use in my Angular webapps, and appended the current time (in ticks) to the URL I'm attempting to open, and that did work:
NSString* originalURL = #"http://somewebservices/data/1234";
NSString* newURL = [NSString stringWithFormat:#"%#?t=%f", originalURL,
[[NSDate date] timeIntervalSince1970]];
NSLog(#"Loading data from: '%#'", newURL);
NSURL *url = [NSURL URLWithString:newURL];
if (url == nil)
return false;
NSError *error;
NSData* urlData = [NSData dataWithContentsOfURL:url options:NSDataReadingUncached error:&error];
(Sigh.)
I'm getting too old for this stuff....
I am very new to iOS development, but I would like to make an app that has two table view controllers (columns): both are a row of images that act as links. The first would be a column of YouTube videos and the second a column of websites. I would like to have all these listed in a file file.txt listed like so: V, http://youtube.com/example W, http://example.com
There would be a long list of those, the V meaning its a video (for the video column) and W for the websites. Now, I understand how to being the single file in, but what happens afterwards is my concern. Can I read each line into some sort of queue and then fire the NSURL request for each one consecutively? How can that be done with NSURL? Is there perhaps a better approach?
There are two questions for me:
Is a text file really the best format?
I might suggest a plist or archive (if the file is only going to exist only in your app's bundle and/or documents folder) or JSON (if it's going to live on a server before delivering it to the user) instead of a text file. It will make it easier to parse this file than a text file. For example, consider the following dictionary:
NSDictionary *dictionary = #{#"videos" : #[#"http://youtube.com/abc", #"http://vimeo.com/xyz"],
#"websites": #[#"http://apple.com", #"http://microsoft.com"]};
You can save that to a plist with:
NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *plistPath = [documentsPath stringByAppendingPathComponent:#"files.plist"];
[dictionary writeToFile:plistPath atomically:YES];
You can add that file to your bundle or whatever, and then read it at a future date with:
dictionary = [NSDictionary dictionaryWithContentsOfFile:plistPath];
You can, alternatively, write that to a JSON file with:
NSError *error = nil;
NSData *data = [NSJSONSerialization dataWithJSONObject:dictionary options:NSJSONWritingPrettyPrinted error:&error];
NSString *jsonPath = [documentsPath stringByAppendingPathComponent:#"files.json"];
[data writeToFile:jsonPath atomically:YES];
You can read that JSON file with:
data = [NSData dataWithContentsOfFile:jsonPath];
dictionary = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
Either way, you can get the list of videos or web sites like so:
NSArray *videos = dictionary[#"videos"];
NSArray *websites = dictionary[#"websites"];
Now that you have your arrays of videos and websites, the question then is how you then use those URLs.
You could do something like:
for (NSString *urlString in videos) {
NSURL *url = [NSURL URLWithString: urlString];
// now do something with the URL
}
The big question is what is the "do something" logic. Because you're dealing with a lot of URLs, you would want to use a NSOperation based solution, not a GCD solution, because NSOperationQueue lets you control the degree of concurrency. I'd suggest a NSOperation-based networking library like AFNetworking. For example, to download the HTML for your websites:
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 4;
for (NSString *urlString in websites)
{
NSURL *url = [NSURL URLWithString:urlString];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
// convert the `NSData` responseObject to a string, if you want
NSString *string = [[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding];
// now do something with it, like saving it in a cache or persistent storage
// I'll just log it
NSLog(#"responseObject string = %#", string);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"error = %#", error);
}];
[queue addOperation:operation];
}
Having said that, I'm not sure it makes sense to kick off a ton of network requests. Wouldn't you really prefer to wait until the user taps on one of those cells before retrieving it (and for example, then just open that URL in a UIWebView)? You don't want an app that unnecessarily chews up the user's data plan and battery retrieving stuff that they might not want to retrieve. (Apple has rejected apps that request too much data from a cellular connection.) Or, at the very least, if you want to retrieve stuff up front, only retrieve stuff as you need it (e.g. in cellForRowAtIndexPath), which will retrieve the visible rows, rather than the hundreds of rows that might be in your text/plist/json file.
Frankly, we need a clearer articulation of what you're trying to do, and we might be able to help you with more concise counsel.
I have an mp3 file on a server. I want to get this file's information like what's the size of this file, what's the artists name, what's the album name, when was the file created, when was it modified, etc. I want all this information.
Is it possible to get this information without actually downloading the whole file? Using NSURLConnection or otherwise?
EDIT:
The following code doesn't give me the required information, i.e. file created by, artist name, etc
NSError *rerror = nil;
NSURLResponse *response = nil;
NSURL *url = [NSURL URLWithString:#"http://link.to.mp3"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:#"HEAD"];
NSData *result = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&rerror];
NSString *resultString = [[[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding] autorelease];
NSLog(#"URL: %#", url);
NSLog(#"Request: %#", request);
NSLog(#"Result (NSData): %#", result);
NSLog(#"Result (NSString): %#", resultString);
NSLog(#"Response: %#", response);
NSLog(#"Error: %#", rerror);
if ([response isMemberOfClass:[NSHTTPURLResponse class]]) {
NSLog(#"AllHeaderFields: %#", [((NSHTTPURLResponse *)response) allHeaderFields]);
}
The "AllHeaderFields" is:
AllHeaderFields: {
"Cache-Control" = "max-age=0";
Connection = "keep-alive";
"Content-Encoding" = gzip;
"Content-Type" = "text/plain; charset=ascii";
Date = "Fri, 17 Feb 2012 12:44:59 GMT";
Etag = 19202n;
Pragma = public;
Server = dbws;
"x-robots-tag" = "noindex,nofollow";
}
It is quite possible to get the ID3 information embedded in an MP3 file (artist name, track title) without downloading the whole file or using low-level APIs. The functionality is part of the AVFoundation framework.
The class to look at is AVAsset and specifically it's network friendly subclass AVURLAsset. AVAsset has an NSArray property named commonMetadata. This commonMetadata property will contain instances of AVMetadataItem, assuming of course that the reference URL contains metadata. You will usually use the AVMetadataItem's commonKey property to reference the item. I find this method of iterating through an array checking commonKeys irritating so I create an NSDictionary using the commonKey property as the key and the value property as the object. Like so:
-(NSDictionary *)dictionaryOfMetadataFromAsset:(AVAsset *)asset{
NSMutableDictionary *metaData = [[NSMutableDictionary alloc] init];
for (AVMetadataItem *item in asset.commonMetadata) {
if (item.value && item.commonKey){
[metaData setObject:item.value forKey:item.commonKey];
}
}
return [metaData copy];
}
With the addition of this simple method the AVAsset's metadata becomes quite easy to use. Here is an example of getting an MP3's metadata through a URL:
NSURL *mp3URL = [NSURL URLWithString:#"http://'AddressOfMP3File'"];
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:mp3URL options:nil];
NSDictionary *metaDict = [self dictionaryOfMetadataFromAsset:asset];
NSLog(#"Available Metadata :%#",metaDict.allKeys);
NSLog(#"title:%#",[metaDict objectForKey:#"title"]);
I have found that this code seems to load just the first few seconds of your MP3 file. Also note that this code is synchronous; So use with caution. But AVURLAsset does have some async functionality described in the docs.
Once you have the AVAsset you can create a AVPlayerItem with it and feed that to an AVPlayer and play it, or not.
Yes and no. Things like the file size and modification date often come as part of the HEAD response. But not always: with a lot of dynamic URLs, you won't get all of the information.
As for the artist and album name, they're part of the MP3's ID3, which is contained inside the file, and so you won't be able to get them with a HEAD request. Since the ID3 tag is typically at the beginning of a file, you could try to grab just that part and then read the ID3 tag. But you won't be able to do it with NSURLConnection since it doesn't support just fetching part of a file, so you'll need to find a more low-level way of getting data by HTTP.
Yep, you're right on target with NSURLConnection.
I think you want to send a HEAD request for the resource you want information about and then check the information you receive in connection:didReceiveResponse: and connection:didReceiveData:
Edit
Admittedly I didn't read your question in its entirety. It won't be possible to get ID3 information, but you should be able to get size of file and maybe creation date etc.
This answer does give some good information about how to get the ID3 information. You'd need to set up a php page to examine the mp3 file server-side and return just that information you require instead of the entire mp3.