In my code I have to use URLWithString to play streaming(HLS) video and fileURLWithPath to play local video.
What is the difference between these two methods?
How should I use single method to play both videos.
Also I need to show last frame as still image when HSL video ends. Its now showing blank screen when it ends. How should i achieve this?
+URLWithString: produces an NSURL that represents the string as given. So the string might be #"http://www.google.com" and the URL represents http://www.google.com.
+fileURLWithPath: takes a path, not a URL, and produces an NSURL that represents the path using a file:// URL. So if you give it /foo/bar/baz the URL would represent file:///foo/bar/baz.
You can of course construct a file URL string manually and pass it to +URLWithString:, but +fileURLWithPath: is simpler to use when you already have a path, as you don't have to deal with escaping the string and coercing it to a URL format.
Similar thing happened in my app which use AVAudioPlayer. I tried with [NSURL URLWithString:path] and found out it fails to open certain mp3 files. I looked into error by a line like [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL URLWithString:path] fileTypeHint:AVFileTypeMPEGLayer3 error:&error], but the error was simply nil
However it was resolved by replacing the url with [NSURL fileURLWithPath:path].
In both case, the path path NSString * #"/var/mobile/Containers/Data/Application/4D96D4AE-2ED4-40B0-85D2-230E1AFA90E7/Documents/01-AudioTrack 01.mp3" 0x1457a8f0 Still I don't know the reason but now I should be careful using [NSURL URLWithString:].
PS. In NSURL Reference document, Apple said as below:
IMPORTANT
To create NSURL objects for file system paths, use fileURLWithPath:isDirectory: instead.
which clearly indicates [NSURL fileURLWithPath:] should be used for open file, though [NSURL URLWithString] also works for some cases.
Related
This is strange, but basically I download and save a video locally, and the store the url path to provide to an AVPlayer to play.
This works fine the first time I do it. I download a file, and then I can play it to my hearts content as many times UNTIL I exit the app. When I launch the app a second time, I now get a black screen when I try to play the same exact video using the same exact path.
Because I am using the Simulator I can verify that the videos and pictures indeed very much still exist in the same folder I saved them to, and I can still play them if I click on them from the Finder.
Maybe it's a caching issue? If it matters, I've saved them straight to the Library directory as I test this.
Relevant Code:
NSString *outputFile = [NSString stringWithFormat:#"video_%#.mp4", guid];
NSString *outputDirectory = [NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *tempPath = [outputDirectory stringByAppendingPathComponent:outputFile];
NSURL *fileURL = [NSURL fileURLWithPath:tempPath];
// save the video to the URL
Then I "persist" it using an NSString [fileURL path] (The way I've built this out, assume the solution requires an NSString to NSURL conversion).
Later I create an AVPlayerItem:
NSURL *url = [NSURL fileURLWithPath:persistedObject.contentURL];
NSLog(#"url: %#", url); // prints a valid location**
AVPlayerItem *item = [AVPlayerItem playerItemWithURL:url];
** for example this is a sample url location
url: file:///Users/gabriel/Library/Developer/CoreSimulator/Devices/CE1FC933-808C-4003-9BE4-DEC59B787FF7/data/Containers/Data/Application/FAD072B4-B5B0-4487-8A76-57B047324A00/Library/picture_D8DEAFA5-0843-4AA3-BB32-C61E32D13579.mp4
It's been suggested I use URLForDirectory:inDomain:appropriateForURL:create:error: and URLByAppendingPathComponent: instead, which I will look into. But still confused as to why it would play when I first download it, but not after app exits when it's the same exact file.
You've made a classic mistake. You are persisting the full path. But the full path changes. Never persist a full path. Only persist the part of the path relative to the value obtained from NSSearchPathForDirectoriesInDomains.
Given what you are doing, you should only persist the base filename (outputFile). Then when the app starts, you rebuild the full path again like you did originally but use the persisted filename to append it to the dynamically obtained path to the application support folder.
So, this seems like it should be super easy, but i'm stumped...
I have an iOS application that I am developing where I am downloading video content from a server, storing it in a custom folder in the Documents, and upon a certain trigger, trying to play the video. I am experiencing some loading errors in my MovieViewController, so am trying to debug the NSURL that is constructed from the file path in a separate standalone application. It is worth noting that the same content works fine when added to the Bundle, but there's quite a lot, so can't afford to do that.
Anyways...
I have set breakpoints in my app and copied out the path of the NSURL that gets loaded into my movie player, and am attempting to hardcode it into an NSURL in my test app. But I can't seem to just assign it with a preexisting value... Eg.
NSURL *url = "file:///var/mobile/Containers/Data/Application/21078F3B-12C5-4D42-8B8B-3C85CB7A0A91/Documents/SecondStory/BloodAlley/MEDIA/copperthief.mp4"
(which is what I copied out of the Variables View of the Debug area).
It gives me the error:
*"Implicit conversion of a non-Objective-C pointer type 'char *' to 'NSURL ' is disallowed with ARC"
... which I cannot seem to track down on SO ....
Of course, I have the NSString representation of the file path before it gets converted to an NSURL, so can just try to reconstruct it, but this got me curious why I couldn't just assign a value...
As the error states, "file:///var/.../copperthief.mp4" is a char * not an NSURL.
To convert it to an NSURL, first you have to get the char *'s NSString representation by adding the # prefix:
#"file:///var/.../copperthief.mp4"
then convert the NSString to an NSURL using URLWithString::
[NSURL URLWithString:#"file:///var/.../copperthief.mp4"];
The first thing is that "..." is not an NSString. It's a C string. An NSString would be #"...", wouldn't it? And even then, if you wanted an NSURL, you'd have to convert from NSString to NSURL, wouldn't you? I mean, you can't assign a string of any kind to an NSSURL variable and expect it to work, can you? This is a computer language; you can't say just any old thing that comes into your head - you have to obey the rules.
The docs for NSURL state that:
An NSURL object represents a URL that can potentially contain the
location of a resource on a remote server, the path of a local file on
disk, or even an arbitrary piece of encoded data.
I have a blob of in-memory data that I'd like to hand to a library that wants to load a resource via an NSURL. Sure, I can first write this NSData to a temp file and then create a file:// NSURL from that, but I'd prefer to have the URL point directly to the buffer that I already have present in memory.
The docs quoted above seem to suggest this is possible, but I can't find any hint of how to accomplish it. Am I missing something?
NSURL supports the data:// URL-Scheme (RFC 2397).
This scheme allows you to build URLs in the form of
data://data:MIME-Type;base64,<data>
A working Cocoa example would be:
NSImage* img = [NSImage imageNamed:#"img"];
NSData* imgData = [img TIFFRepresentation];
NSString* dataFormatString = #"data:image/png;base64,%#";
NSString* dataString = [NSString stringWithFormat:dataFormatString, [imgData base64EncodedStringWithOptions:0]];
NSURL* dataURL = [NSURL URLWithString:dataString];
Passing around large binary blobs with data URLs might be a bit inefficient due to the nature of base64 encoding.
You could also implement a custom NSURLProtocol that specifically deals with your data.
Apple has some sample code that uses a custom protocol to pass around image objects: https://developer.apple.com/library/mac/samplecode/SpecialPictureProtocol/Introduction/Intro.html#//apple_ref/doc/uid/DTS10003816
What you are missing is the NSURLProtocol class. Takes about three dozen lines of code, and any code that handles URLs properly can access your in-memory data. Read the documentation, it's not difficult and there is sample code available.
Unfortunately there are some APIs that take an NSURL as a parameter, but can only handle file URLs.
I have found that so far the path sent to application:openURL:sourceApplication:annotation: is:
file://localhost/private/var/mobile/Applications/<GUID>/Documents/Inbox/file
To check that the filesystem operations that I am about to perform are indeed likely to succeed (and that the url given to me is not a location outside the sandbox), it looks like I have to do this:
NSString* hdurl = [[#"file://localhost/private" stringByAppendingString:NSHomeDirectory()] stringByAppendingString: #"/"];
NSString* path = url.absoluteString;
if ([path hasPrefix:hdurl]) {
// now ready to e.g. call fopen on: [path substringFromIndex:#"file://localhost".length]
Now, I seem to vaguely recall (and this is probably wrong) that in the past I have seen the file:/// style URL being used. That would clearly cause this code to fail.
How am I to know that it will always give me a file://localhost URL prefix?
Apple's documentation on URLs is strangely missing a section on file URLs.
An NSURL that points to a file on the local file system is called a "file URL". To convert the NSURL to an NSString representing the file's path you use:
NSString *filePath = [url path];
To check to see if an NSURL represents a file URL, use:
BOOL isFileURL = [url isFileURL];
Keep in mind that if your app is passed a file URL, you will always have access to the file. There is no need to check if it starts with any prefix. Why would iOS pass you a file that you don't have access to?
I have a webview which i want to load using the loadHtmlString method. The problem is that I want to be able to change the img src's with images that i have previously downloaded. I also use google analitics in the html so I need to set the baseUrl to the actual url so it will work. Here comes the problem. If I put the baseUrl in, the images will not load. If I don't set the baseUrl, it works. How can I get around this, so I will be able to both use google analitycs and have the images store locally in my application? I would prefer not having to implement the google analitics sdk in my project.
A strange thing is that if I run it in simulator, and not put the "http://" prefix in front of my baseUrl, it works fine. However, when I run it on a device, I receive the following error and it doesn't work:
Domain=WebKitErrorDomain Code=101 "The URL can’t be shown"
Thanks
EDIT
If I do this, it works:
[appsWebView loadHTMLString:htmlString baseURL:nil];
However, I must provide a baseURL in order to have Google Analitics working, I have two further cases:
This one gives the above mentioned error: (it works ok in simulator but gives error when running on device)
[appsWebView loadHTMLString:htmlString baseURL:[NSURL urlWithString:#"test.com"]];
This one simply doesn't show anything: (neither loads the html string or the url)
[appsWebView loadHTMLString:htmlString baseURL:[NSURL urlWithString:#"http://test.com"]];
I incorrectly assumed that the problem was that the local image was not fully specifying the full path, but that does not appear to be the problem here. But, you are quite right that it appears (somewhat surprisingly) that you cannot specify some web-based baseURL and also reference a local image in your HTML string. No simple solutions are leaping out at me, but at the very least, it appears that you might have a couple of (not very good) options:
First, you could base64 encode the local image using some base64 library like Mike Gallagher's NSData+Base64 category, e.g.:
NSData *imageData = [NSData dataWithContentsOfFile:imagePath];
NSString *imageDataBase64 = [imageData base64EncodedString];
NSString *imageHtml = [NSString stringWithFormat:#"<img src='data:image/png;base64,%#'>", imageDataBase64];
This slows the initial rendering, but maybe it's better than nothing.
Second, you could always try leaving the baseURL as nil, removing the JavaScript that does the Google Analytics from the HTML string, and then try injecting that JavaScript via stringByEvaluatingJavaScriptFromString. This approach may or may not work depending upon the complexity of the Google Analytics JavaScript (e.g. what further web-based references it might have), but there's a outside chance you might be able to do something that way.
My apologies for assuming the problem was a trivial img URL. Clearly you had identified a more fundamental issue.
Original answer:
Create your image URLs in your HTML string to be fully qualified file URLs within your local file system:
The image is either in Documents:
NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *imagePath = [documentsPath stringByAppendingPathComponent:imageName];
Or in the bundle:
NSString *imagePath = [[NSBundle mainBundle] pathForResource:imageName
ofType:nil];
But, once you have fully qualified path, you should be able to use that:
NSURL *imageUrl = [NSURL fileURLWithPath:imagePath];
NSString *imageHtml = [NSString stringWithFormat:#"<img src='%#'>", imageUrl];
I would bet it's a casing issue. Take into account that the Device is case sensitive whereas the Simulator is not. Check the URL and make sure it contains the right characters.