I'm currently developing an Obj-C Desktop application which gets a string from an URL and displays an image regarding to the recieved string.
//I know this one won't work, but it's just for example
NSString * text = [NSString stringFromUrl:#"http://example.com"];
NSString * imageName = [text splitStringIntoSome];
//imageName is now #"A.png"
[imageViewOutlet setImage:[NSImage imageNamed:imageName];
So, the problem is, I want to do that when the application launches, but when I copy this code into my applicationDidFinishLaunching, just nothing happens...
Unfortunately since URL requests are performed asynchronously, it requires a bit more code to do this. Here is a good example straight from Apple:
Using NSURLConnection
Except in - (void)connectionDidFinishLoading:(NSURLConnection *)connection you would create an image using NSImage's - (id)initWithData:(NSData *)data
Related
In iOS 6 the QLPreviewController no longer loads a PDF from a URL. It works fine in iOS 5. I have implemented the QLPreviewControllerDataSource methods as documented here.
#pragma mark - QLPreviewControllerDataSource
- (NSInteger)numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller {
return 1;
}
- (id <QLPreviewItem>) previewController: (QLPreviewController *) controller previewItemAtIndex: (NSInteger) index;
{
NSURL *fileURL = [NSURL URLWithString:#"http://www.bliley.net/XTAL/PDF_Instructions/Test_File.pdf"];
return fileURL;
}
This works perfectly in iOS 5, however in iOS 6 the console outputs:
Couldn't issue file extension for path: /XTAL/PDF_Instructions/Test_File.pdf
Have you tried using fileURLWithPath instead of URLWithString? I had other issues that were fixed by doing so.
Also not sure if QLPreviewController will handle remote URLs. If not, you could download the file and then display it.
I downloaded the file from remote url and saved locally, then I display the PDF using the QLPreviewController .In iOS 6 its working.
First i saved the file from remote url using the following code :
NSString *local_location;
NSString *path = [[NSBundle mainBundle] pathForResource:#"sampleData" ofType:#"plist"];
path = NSTemporaryDirectory();
local_location= [path stringByAppendingPathComponent:[NSString stringWithFormat:#"My_Invoice.pdf"]];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString: remoteurl]];
[request setDownloadDestinationPath:local_location];
[request startSynchronous];
For showing the Pdf :
QLPreviewController* preview = [[QLPreviewController alloc] init];
preview.dataSource = self;
[self presentModalViewController:preview animated:YES];
QLPreviewController delegate methods are :
- (NSInteger) numberOfPreviewItemsInPreviewController: (QLPreviewController *) controller
{
return 1;
}
- (id <QLPreviewItem>)previewController:(QLPreviewController *)controller previewItemAtIndex:(NSInteger)index
{
return [NSURL fileURLWithPath:local_location];
}
I am having a similar issue and seems like it might stem from a stricter enforcement of the file-type URL of QLPreviewItem
#property (readonly) NSURL *previewItemURL;
Discussion
This property is used by a Quick Look preview controller to get an item’s URL. In typical use, you would implement a getter method in your preview item class to provide this value.
The value of this property must be a file-type URL.
If the item is not available for preview, this property’s getter method should return nil. In this case, the Quick Look preview controller displays a “loading” view.
Availability
Available in iOS 4.0 and later.
Declared In
QLPreviewItem.h
UPDATE: I have opened a bug with Apple dealing with this issue for iOS 6 and it seems they have aced it as a bug so may offer a fix in the near future. The bug I opened had to do with using custom NSURLProtocols for the preview, but may apply to other aspects as well.
Link to class
But note that QLPreviewController expects a URL to a local resource
You would need to download and save the PDF file locally first and then create a proper file URL to the local file.
I am attempting to create an application that goes through various images from the net and aim to cache them onto the iPhone for offline use. The code I am currently working with is:
NSMutableDictionary *Cache;
- (UIImage *)CachedImage: (NSString*)url {
UIImage *image = [Cache objectForKey:url];
if (image == nil) {
image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:url]]];
[Cache setObject:image forKey:url];
//NSLog (#"Stored");
return image;
} else {
//NSLog (#"Taken");
return image;
} }
I call the function and place the image into an ImageView using the strip of code below.
[self.imageView setImage:[self CachedImage:url]]; // Change url to desired URL.
Using the NSLog, the problem I found is that the code doesn't actually store the value because the value is always reading nil. Why is that and are there other ways of storing images for offline use?
Thanks in advance.
-Gon
Use NSCache to cache UIImages. You can also save the image locally (if you reuse these images a lot and during multiple launch) so whenever your app closes or you flush your cache, you can get the images immediately from your local directory.
https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/NSCache_Class/Reference/Reference.html
You are looking for
NSCache
Check it out here: http://nshipster.com/nscache/
Poor NSCache, always being overshadowed by NSMutableDictionary in the
most inappropriate circumstances. It’s like no one knows its there,
ready to provide all of that garbage collection behavior that
developers take great pains to re-implement themselves.
I processed drag operation from browser view to custom view.It work well in snow lepoard,but not in Mountain Lion with sandbox.
in browser view:
NSMutableArray* urls = [[[NSMutableArray alloc] init] autorelease];
..............put some NSUrl to urls array....................
[pasteboard writeObjects:[NSArray arrayWithArray:urls]];
in my receive custom view:
NSArray* pasteboardItems = [pasteboard readObjectsForClasses:[NSArray arrayWithObject:[NSString class]] options:nil];
NSArray* pasteboardItems2 = [pasteboard readObjectsForClasses:[NSArray arrayWithObject:[NSURL class]] options:nil];
NSArray* pasteboardItems3 = [pasteboard readObjectsForClasses:[NSArray arrayWithObject:[NSImage class]] options:nil];
NSLog(#"%#",pasteboardItems);
NSLog(#"%#",pasteboardItems2);
NSLog(#"%#",pasteboardItems3);
my log is:
2012-08-09 18:33:43.886 iCollage[6885:303] __CFPasteboardIssueSandboxExtensionForPath: error for [/Users/xxxx/Library/Containers/xxxxxxxxxxxx/Data/Downloads/1343902069.jpg]
2012-08-09 18:33:44.546 iCollage[6885:303] ( "file://localhost/Users/xxx/Library/Containers/xxxxxxxx/Data/Downloads/1343902069.jpg")
2012-08-09 18:33:44.547 iCollage[6885:303] ( "file://localhost/Users/xxxxx/Library/Containers/xxxxxx/Data/Downloads/1343902069.jpg")
2012-08-09 18:33:44.547 iCollage[6885:303] ()
my question is:
1.how to fix this error __CFPasteboardIssueSandboxExtensionForPath;I refer the docs and found nothing about that.I am ensuer that i have the permission to access the file!google says, may be "startAccessingSecurityScopedResource" will help me, then i try and failed
2.why pasteboardItems2 have value?i write to pasteboard only url but not string.It disgusted me that I can get the url both from NSString type and NSUrl type! (I try drag a file from iFinder, the url will only exist in pasteboardItems but not pasteboardItems2).Anybody know why? I think the first problem will auto fixed when some one help me fix this problem.
I believe Apple answer question 1:
Important: Although you can support dragging file paths, in general,
you should avoid doing so unless you are certain that the destination
app will never be run in an app sandbox. If you use an NSString, OS X
has no way to know whether that string should be interpreted as a
path; thus, OS X does not expand the destination app’s sandbox to
allow access to the file or directory at that location. Instead, use
an NSURL, a bookmark, or a filename pasteboard type.
WRT to question 2, it looks like you have pasted URLs so reading NSURL objects would seem to be correct. However I think you should implement the dragging using the following code (also from the link above):
- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender
{
NSPasteboard *pboard = [sender draggingPasteboard];
if ( [[pboard types] containsObject:NSFilenamesPboardType] ) {
NSArray *files = [pboard propertyListForType:NSFilenamesPboardType];
int numberOfFiles = [files count];
// Perform operation using the list of files
}
return YES;
}
You need to generate security-scoped URL bookmark data on the sender side, and turn that data back into a URL on the receiver side. There's some other stuff you have to do after that when you want to actually access the URL; the documentation elaborates.
The receiving application, when running in a sandbox, will not be able to handle bare paths. This is a core part of being sandboxed; you are not allowed to use bare paths or their corresponding URLs to access files that aren't in your sandbox container and haven't been explicitly handed to you by the user.
Your pasteboardItems read object of NSString type, but you dragged a file(with jpg extension), you should register for NSString type in your init method:
[self registerForDraggedTypes:[NSArray arrayWithObject:NSPasteboardTypeString]];
You need to have Document Types defined in your application so that the sandboxing mechanism knows your application should be opening files with those extensions. You can do this by clicking the project on the left in Xcode, and in the Info tab, under Document Types add a new document type for each extension.
You just need to fill in the name and extensions field.
Also if you want to persist your permission to access the files dragged onto your application, you can use this class to wrap up all that logic. https://github.com/leighmcculloch/AppSandboxFileAccess
My tableview is get XML data from URL,First I declare a NSMutableArray *dataArray;
and this is how I get the data in my TableviewSample.m
- (void)getDataFromURL{
NSString *theURLAsString = [NSString stringWithFormat:GetAllData];//<-EXE_BAD_ACCESS HERE
//#define stringWithFormat:GetAllData #"http://192.168.10.28/req_alldata.php"
NSURL *theURL = [NSURL URLWithString:theURLAsString];
self.dataArray = [NSMutableArray arrayWithContentsOfURL:theURL];
}
Then I just get the elements form this array to my tableview ...
But here I have to say one more thing , actually it won't crash before I add another view...
I add a bar button to go to a webView , this webView is use to load a IP Cam stream video
When I back to the tableview , It will appear EXC_BAD_ACCESS
This is odd things I cannot to solve it...because both side code are all looks normal
If I remove this webview ,no matter how I run the program ,it won't crash...
And sometimes I leave the webView I will receive memory warning :level 2
But just only one time.
or do I use a wrong way to open an ip cam stream ???
Thanks for all reply : )
OK,here is the code different I use in my webview class
This is first version I use
- (void)viewDidAppear:(BOOL)animated{
NSString *directGoToWebCam = [NSString stringWithFormat:GetAllData];
self.IPCamWebView=[[[UIWebView alloc] initWithFrame:CGRectMake(0,0,640,960)] autorelease];
[self.IPCamWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:directGoToWebCam]]];
[self.view addSubview:self.IPCamWebView];
}
Where does GetAllData come from? It looks like that isn't pointing to anything. More code, the exact error, and a more careful description will go a long way here.
It probably has something to do with the use of #define which does not say anything about the type of the object you are using.
If you want to define a constant string in your code the best would be to use something like this:
static NSString *GetAllData = #"192.168.10.28/req_alldata.php";
Where you need to use the string you can simply write:
NSString *GoToWebCam = [NSString stringWithString:GetAllData];
I'm using QTKit to progressively download and play an MP3 from a URL. According to this documentation, this is the code I should use to accomplish that:
NSURL *mp3URL = [NSURL URLWithString:#"http://foo.com/bar.mp3"];
NSError *error = nil;
QTMovie *sound = [[QTMovie alloc] initWithURL:mp3URL error:&error];
[sound play];
This works, and does exactly what I want — the MP3 URL is lazily downloaded and starts playing immediately. However, if the URL does not have the ".mp3" path extension, it fails:
NSURL *mp3URL = [NSURL URLWithString:#"http://foo.com/bar"];
NSError *error = nil;
QTMovie *sound = [[QTMovie alloc] initWithURL:mp3URL error:&error];
[sound play];
No error is given, no exception is raised; the duration of the sound is just set to zero, and nothing plays.
The only way I have found to work around this is to force a type by loading the data manually and using a QTDataReference:
NSURL *mp3URL = [NSURL URLWithString:#"http://foo.com/bar"];
NSData *mp3Data = [NSData dataWithContentsOfURL:mp3URL];
QTDataReference *dataReference =
[QTDataReference dataReferenceWithReferenceToData:mp3Data
name:#"bar.mp3"
MIMEType:nil];
NSError *error = nil;
QTMovie *sound = [[QTMovie alloc] initWithDataReference:dataReference error:&error];
[sound play];
However, this forces me to completely download ALL of the MP3 synchronously before I can start playing it, which is obviously undesirable. Is there any way around this?
Thanks.
Edit
Actually, it seems that the path extension has nothing to do with it; the Content-Type is simply not being set in the HTTP header. Even so, the latter code works and the former does not. Anyone know of a way to fix this, without having access to the server?
Edit 2
Anyone? I can't find information about this anywhere, and Google frustratingly now shows this page as the top result for most of my queries...
Two ideas. (The first one being a bit hacky):
To work around the missing content type, you could embed a small Cocoa webserver that supplements the missing header field and route your NSURL over that "proxy".
Some Cocoa http server implementations:
http://code.google.com/p/cocoahttpserver/
http://cocoawithlove.com/2009/07/simple-extensible-http-server-in-cocoa.html
http://culturedcode.com/cocoa/
The second one would be, to switch to a lower level framework (From QTKit to AudioToolbox).
You'd need more code, but there are some very good resources out there on how to stream mp3 using AudioToolbox.
e.g.:
http://cocoawithlove.com/2008/09/streaming-and-playing-live-mp3-stream.html
Personally I'd go with the second option. AudioToolbox isn't as straightforward as QTKit but it offers a clean solution to your problem. It's also available on both - iOS and Mac OS - so you will find plenty of information.
Update:
Did you try to use another initializer? e.g.
+ (id)movieWithAttributes:(NSDictionary *)attributes error:(NSError **)errorPtr
You can insert your URL for the key QTMovieURLAttribute and maybe you can compensate the missing content type by providing other attributes in that dictionary.
This open source project has a QTMovie category that contains methods to accomplish similar things:
http://vidnik.googlecode.com/svn-history/r63/trunk/Source/Categories/QTMovie+Async.m
If you thought weichsel's first solution was hacky, you're going to love this one:
The culprit is the Content-Type header, as you have determined. Had QTKit.framework used Objective-C internally, this would be a trivial matter of overriding -[NSHTTPURLResponse allHeaderFields] with a category of your choosing. However, QTKit.framework (for better or worse) uses Core Foundation (and Core Services) internally. These are both C-based frameworks and there is no elegant way of overriding functions in C.
That said, there is a method, just not a pretty one. Function interposition is even documented by Apple, but seems to be a bit behind the times, compared to the remainder of their documentation.
In essence, you want something along the following lines:
typedef struct interpose_s {
void *new_func;
void *orig_func;
} interpose_t;
CFStringRef myCFHTTPMessageCopyHeaderFieldValue (
CFHTTPMessageRef message,
CFStringRef headerField
);
static const interpose_t interposers[] __attribute__ ((section("__DATA, __interpose"))) = {
{ (void *)myCFHTTPMessageCopyHeaderFieldValue, (void *)CFHTTPMessageCopyHeaderFieldValue }
};
CFStringRef myCFHTTPMessageCopyHeaderFieldValue (
CFHTTPMessageRef message,
CFStringRef headerField
) {
if (CFStringCompare(headerField, CFSTR("Content-Type"), 0) == kCFCompareEqualTo) {
return CFSTR("audio/x-mpeg");
} else {
return CFHTTPMessageCopyHeaderFieldValue(message, headerField);
}
}
You might want to add logic specific to your application in terms of handling the Content-Type field lest your application break in weird and wonderful ways when every HTTP request is determined to be an audio file.
Try replacing http:// with icy://.
Just create an instance like this...
QTMovie *aPlayer = [QTMovie movieWithAttributes:[NSDictionary dictionaryWithObjectsAndKeys:
fileUrl, QTMovieURLAttribute,
[NSNumber numberWithBool:YES], QTMovieOpenForPlaybackAttribute,
/*[NSNumber numberWithBool:YES], QTMovieOpenAsyncOKAttribute,*/
nil] error:error];