I'm doing an app which downloads info via a request to a website, giving me back and HTML and parsing this data I obtain my app info. For downloading this data I'm using, using a url with all the parameters the request needs at the end.
NSData *data = [NSData dataWithContentsOfURL:url];
NSString* htmlString;
htmlString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
[self parserHTML:htmlString]; // here I fill a NSArray with the info parsed
[self searchSomething:htmlString]; // continue filling the NSArray
...
The task for download the data and parser the HTML takes long time.
What can I do to make this faster? Grand Central Dispatch? If so, how can I use it, because I'm using this and it doesn't works, because the NSSArray is empty:
dispatch_queue_t downloadQueue = dispatch_queue_create("pharmacy downloader", NULL);
dispatch_async(downloadQueue, ^{
NSData *data = [NSData dataWithContentsOfURL:urlReal];
NSString* htmlString;
htmlString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
[self parserHTML:htmlString]; // here I fill a NSArray with the info parsed
[self searchSomething:htmlString]; // continue filling the NSArray
});
dispatch_release(downloadQueue);
If I don't use GCD it works. What can be the problem??
Thanks for your help. I'm totally lost!!! :S
Use NSURLDownload or NSURLConnection instead.
For some sample code you may take a look at QuickLookDownloader
Related
So, I'm trying to open a .mobileprovisioning profile to read what's inside... this is what I'm doing:
NSString *path = [pathURL path];
NSData *data = [[NSFileManager defaultManager] contentsAtPath:path];
Of course I get the data read but I'm not finding the way of getting of get this data into something useful... an NSDictionary, an NSString or whatever...
I've already tried:
NSString *newStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
Any idea? I'm sure this is an encoding issue, but I can't solve it after reading and googling for some time... I think the provisioning profile is saved as hexadecimal, but I don't know how to read that from objective-c. I have found this but there wasn't an useful answer.
How to convert NData populated with hex values to NSString
Thanks!
The following method should do what you want. As #rbrockerhoff says the mobile provisioning profile is an encoded CMS message. This method uses a decoder to first decode the data using the CMS functions and then creates the plist string/contents from the decoded data. This string can then be converted into a dictionary which is returned from the method. The dictionary will contain all the details from the mobile provisioning profile.
- (NSDictionary *)provisioningProfileAtPath:(NSString *)path {
CMSDecoderRef decoder = NULL;
CFDataRef dataRef = NULL;
NSString *plistString = nil;
NSDictionary *plist = nil;
#try {
CMSDecoderCreate(&decoder);
NSData *fileData = [NSData dataWithContentsOfFile:path];
CMSDecoderUpdateMessage(decoder, fileData.bytes, fileData.length);
CMSDecoderFinalizeMessage(decoder);
CMSDecoderCopyContent(decoder, &dataRef);
plistString = [[NSString alloc] initWithData:(__bridge NSData *)dataRef encoding:NSUTF8StringEncoding];
NSData *plistData = [plistString dataUsingEncoding:NSUTF8StringEncoding];
plist = [NSPropertyListSerialization propertyListWithData:plistData options:NSPropertyListImmutable format:nil error:nil]
}
#catch (NSException *exception) {
NSLog(#"Could not decode file.\n");
}
#finally {
if (decoder) CFRelease(decoder);
if (dataRef) CFRelease(dataRef);
}
return plist;
}
A .mobileprovisioning file is an encoded CMS message.
See https://developer.apple.com/library/mac/documentation/security/Reference/CryptoMessageRef/Reference/reference.html for details and an API for decoding it.
If you just want the encoded property list as text, a quick-and-dirty hack is to get the byte pointer for your NSData, scan for the beginning "<?xml" and up to the closing "</plist>". Then make a NSString from that.
You can simply force to open the mobile provisioning profile in TextEdit where you can see the
interior contents and in which you can trim/Edit the encoded CMS message or whatever you want . Then you can simply decode with NSData encodewithUTF string method.
Hope this helps.
i have one NSMutableArray with some image url's. The images have sizes between 12KB to 6MB. I use AsycImageView class and implement but when large images are downloading application get crashed, I gave 6*1024*1024 (6MB) for maxsize in that class, increase time interval 60.0 sec to 180.o sec, but there is no use. I'm getting an error "Received memory warning" and when app crash automatically connection remove from device, but in simulator there is no crash.
Use GCD for lazy loading.
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
NSString *strURL = url here;
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:strURL]];
UIImage *image = nil;
if(data)
image = [UIImage imageWithData:data];
dispatch_sync(dispatch_get_main_queue(), ^{
//now use image in image View or anywhere according to your requirement.
if(image)
yourImgView = image
});
});
you can do this using multiThreading. Here is a code
- (UIImageView *)getImageFromURL:(NSDictionary *)dict
{
#ifdef DEBUG
NSLog(#"dict:%#", dict);
#endif
UIImageView *_cellImage = nil;
_cellImage = ((UIImageView *)[dict objectForKey:#"image"]);
NSString *strURL = [dict objectForKey:#"imageurl"]);
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:strURL]];
#ifdef DEBUG
NSLog(#"%i", data.length);
#endif
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *dataFilePath = [NSString stringWithFormat:#"%#.png", [documentsDirectory stringByAppendingPathComponent:[dict objectForKey:#"imageid"]]];
if (data) // i.e. file exist on the server
{
[data writeToFile:dataFilePath atomically:YES];
_cellImage.image = [UIImage imageWithContentsOfFile:dataFilePath];
}
else // otherwise show a default image.
{
_cellImage.image = [UIImage imageNamed:#"nouser.jpg"];
}
return _cellImage;
}
And call this method in cellForRowAtIndexPath like this:
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:imageURL, #"imageurl", self.imgPhoto, #"image", imageid, #"imageid", nil];
[NSThread detachNewThreadSelector:#selector(getImageFromURL:) toTarget:self withObject:dict];
The code will start getting images in multiple threads and will save image locally to document folder. Also the image will not download again if already exists with the same name. Hope this helps
You could download image asynchronously using GCD. Use the following code,
__block NSData *imageData;
dispatch_queue_t myQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, NULL);
dispatch_async(myQueue, ^{
//load url image into NSData
imageData = [NSData dataWithContentsOfURL: your_image_URL];
if(imageData) {
dispatch_sync(dispatch_get_main_queue(), ^{
//convert data into image after completion
UIImage *img = [UIImage imageWithData:imageData];
//do what you want to do with your image
});
} else {
NSLog(#"image not found at %#", your_image_URL);
}
});
dispatch_release(myQueue);
For further info, see dispatch_queue_t
I would recommend a drop in replacement API SDWebImage it provides a category for UIImageVIew with support for remote images coming from the web. you can also have a placeholder image till the images are downloaded Asynchronously
. Its easy to use and saves a lot of work
You're problem seems to be more of a memory usage issue than it is a performance issue.
If you really want to download image asynchronously I would recommend you use The UIImageView category from AFNetworking which has been fully tested and is very well maintained.
However here you run into memory warnings on your device (which obviously holds much less memory than your simulator which runs on your Mac).
So I would use first the static analyzer:
to see if leaks are present and then run a Leaks Instrument to track it down.
Hope this helps.
I have a UITableView which displays fetched RSS dynamically, I have now customized the RSS to return the image name so that i can later on add a UIImageView to to every cell in the table which displays the image beside every cell, here is the code for adding the image
UIImageView *imageView = [[UIImageView alloc] init];
imageView.frame = CGRectMake(0, 0, 40, 40);
NSString *path = [NSString stringWithFormat:#"URL/%#",object.imageName]; //"object" is the returned Object from the RSS, so basically what i am doing is appending the image name to the path url.
NSURL *url = [NSURL URLWithString:path];
NSData *data = [NSData dataWithContentsOfURL:url];
imageView.image = [UIImage imageWithData:data];
[cell addSubview:imageView];
[cell bringSubviewToFront:imageView];
so when i run my app the app runs slowly and even stops for a small amount of time, the reason for that is that i am loading all RSS imaged directly in this line NSData *data = [NSData dataWithContentsOfURL:url];
any solution for this problem ?
Thank you in advance
i actually thought of fetching the images in a separate thread,
dispatch_queue_t fetchImage = dispatch_queue_create("Fetching Image", NULL);
dispatch_async(fetchImage, ^{
NSData *data = [NSData dataWithContentsOfURL:url];
});
dispatch_release(fetchImage);
but doing so wont allow me to use the variable "data" outside the queue.
any idea ?
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSString *path = [NSString stringWithFormat:#"URL/%#",object.imageName];
NSURL *url = [NSURL URLWithString:path];
NSData *data = [NSData dataWithContentsOfURL:url];
dispatch_async(dispatch_get_main_queue(), ^{
imageView.image = [UIImage imageWithData:data];
}); });
The method [NSData dataWithContentsOfURL:] is synchronous: whenever you call it, it blocks the current thread (which is almost certainly your app's main thread) for as long as it takes to complete. This is very bad. Aside from making the UI feel janky, there's a watchdog process that will kill unresponsive apps.
You really, really want to use asynchronous network calls. Read up on NSURLConnection, but know, also, that there are many articles and libraries and samples out there on this exact subject: loading images asynchronously for display in a table view. Start with, maybe, AFNetworking's category on UIImageView, or maybe a library like SDWebImage.
You should retrieve your data asynchronously ! May be the use of a Open Source libraries will help you:
AFNetworking
ASIHTTPRequest - not recommended
Or you can also use the NSURLConnection class with the asynchronous mode.
I'm sure this has been asked before, but I've had no luck finding it. In my app data is loading synchronously, which locks up the app. I've tried asynch loading, but that doesn't work with the JSON parser.
To denote that the app isn't frozen, just working on downloading data, I was hoping to present the user with a small transparent overlay with the loading icon. I was wondering how to go about this - do I need to put it on another thread?
To clarify, I want to do something very similar to the Netflix iPad app - their loading overlay is perfect for the projet I'm working on.
Edit: I've added some async code below
I first call this function:
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSURLConnection *c = [[NSURLConnection alloc] init];
[self connectionWorks:c didReceiveData:data];
connectionworks
-(void)connectionWorks:(NSURLConnection *)connection didReceiveData:(NSData *)data{
OLWork *newWork;
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSDictionary *results = [jsonString JSONValue];
NSArray *rawBooks = [results objectForKey:#"works"];
for (NSDictionary *work in rawBooks) {
newWork = [[OLWork alloc] init];
newWork.title = [work objectForKey:#"title"];
newWork.author = [[[work objectForKey:#"authors"] objectAtIndex:0] objectForKey:#"name"];
newWork.key = [work objectForKey:#"key"];
[self.works setValue:newWork forKey:newWork.title];
}
}
This will do the job for you, it's well documented and easy to use
https://github.com/jdg/MBProgressHUD
Out of intrest which JSON parser are you using? Getting asynchronous requests working would be a much better solution.
I'm trying to combine images in my app into one file and write it to disk.
NSMutableArray *array = [NSMutableArray arrayWithObjects:
[NSData dataWithContentsOfFile:#"0.png"],
[NSData dataWithContentsOfFile:#"1.png"],
[NSData dataWithContentsOfFile:#"2.png"],
nil];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSError *error = nil;
NSString *path=#"/Users/myusername/Desktop/_stuff.dat";
[data writeToFile:path options:NSDataWritingAtomic error:&error];
or
NSArray *array = [NSArray arrayWithObjects:
[NSImage imageNamed:#"0"],
[NSImage imageNamed:#"1"],
[NSImage imageNamed:#"2"],
nil];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSError *error = nil;
NSString *path=#"/Users/myusername/Desktop/_stuff.dat";
[data writeToFile:path options:NSDataWritingAtomic error:&error];
But both produce a file that is 4KB (empty). If I NSLog the error it is (null). Am I making the data the wrong way?
Edit: If I open the resulting file with a text editor, it looks like this:
I wrote a quick example:
Missing: memory management / error handling / proper file handling
// Archive
NSMutableArray *array = [[NSMutableArray alloc] init];
NSString * input = #"/Users/Anne/Desktop/1.png";
[array addObject:[NSData dataWithContentsOfFile:input]];
[array addObject:[NSData dataWithContentsOfFile:input]];
[array addObject:[NSData dataWithContentsOfFile:input]];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSString *path = #"/Users/Anne/Desktop/archive.dat";
[data writeToFile:path options:NSDataWritingAtomic error:nil];
// Unarchive
NSMutableArray *archive = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
NSData * firstObject = [archive objectAtIndex:0];
NSString * output = #"/Users/Anne/Desktop/2.png";
NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:output];
[firstObject writeToURL:fileURL atomically:YES];
You can also add NSImages to the NSMutableArray:
NSString * input = #"/Users/Anne/Desktop/1.png";
NSImage *image = [[NSImage alloc] initWithContentsOfFile: input];
[array addObject:image];
But that will significantly increase the file size.
Response to the following comment:
So if I only need to access an image at runtime (in the archive), is there a way to access that image at an index without unarchiving the whole thing? Seems like unnecessary overhead to me.
I assume you're still struggling with this problem?
Hiding (or encrypting) app resources?
Like i mentioned earlier, combining all files into one big file does the trick.
Just make sure you remember the file-length of each file and file-order.
Then you can extract any specific file you like without reading the whole file.
This might be a more sufficient way if you only need to extract one file at the time.
Quick 'dirty' sample:
// Two sample files
NSData *fileOne = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/1.png"];
NSData *fileTwo = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/2.png"];
// Get file length
int fileOneLength = [fileOne length];
int fileTwoLength = [fileTwo length];
// Combine files into one container
NSMutableData * container = [[NSMutableData alloc] init];
[container appendData:fileOne];
[container appendData:fileTwo];
// Write container to disk
[container writeToFile:#"/Users/Anne/Desktop/container.data" atomically:YES];
// Read data and extract sample files again
NSData *containerFile = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/container.data"];
NSData *containerFileOne =[containerFile subdataWithRange:NSMakeRange(0, fileOneLength)];
NSData *containerFileTwo =[containerFile subdataWithRange:NSMakeRange(fileOneLength, fileTwoLength)];
// Write extracted files to disk (will be exactly the same)
[containerFileOne writeToFile:#"/Users/Anne/Desktop/1_extracted.png" atomically:YES];
[containerFileTwo writeToFile:#"/Users/Anne/Desktop/2_extracted.png" atomically:YES];
// Only extract one file from the container
NSString * containerPath = #"/Users/Anne/Desktop/container.data";
NSData * oneFileOnly = [[NSFileHandle fileHandleForReadingAtPath:containerPath] readDataOfLength:fileOneLength];
// Write result to disk
[oneFileOnly writeToFile:#"/Users/Anne/Desktop/1_one_file.png" atomically:YES];
Tip:
You can also save the 'index' inside the container file.
For example: The first 500 bytes contain the required information.
When you need a specific file: Read the index, get the file position and extract it.
You are archiving a NSMutable array of NSImage. This two classes conform to the NSCoding protocol required by NSKeyedArchiver, so I don't see where would be your problem.
So, here are many ideas to test.
First, are you sure that the data you think you have are valid? In your first code snippet, you write [NSData dataWithContentsOfFile:#"0.png"]. This method expects an absolute file path.
Assuming the problem is not in your code, just in your question, let's continue:
Do you have something different than nil in the variable data after your archiving? Ie, after the assignement to data, can you add this code. If the assertion fail, you will get an exception at runtime:
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSAssert(nil != data, #"My object data is nil after archiving");
If the problem was not here, what is the return of the line [data writeToFile:path options:NSDataWritingAtomic error:&error];
(Not the variable error, but the return value of the call to the method - writeToFile: options: error:)
What happens if you simplify your code and just do this:
result = [NSKeyedArchiver archiveRootObject:data
toFile:archivePath];
If everything was ok, have you tried to unarchive your file with NSKeyedUnarchiver?
The problem is that [NSData dataWithContentsOfFile:#"0.png"] looks for the file "0.png" in the current directory, but what the application thinks of as the current directory is probably not the place you're expecting. For graphical apps, you should always either use an absolute path or a path relative to some place that you can get the absolute path of (e.g. your app bundle, the application support directory, some user-selected location).
For command-line tools, using the current directory is more common. But I doubt that's the case here.
Another thing I noticed on Mavericks and up is that the folders in the path must be in existence. Meaning you must create the folder structure prior to saving into that folder. If you try to write to a folder on the desktop or elsewhere, even with sandboxing off, it will fail if the folder does not exist. I know this has been answered already, but I found that my issue continued regardless, but once I make sure that the folder structure was in place, I could do my writing to that folder.
On a side note: I'm sure that you could do this from NSFileManager, and I'll be doing that myself once I finalize my app structure, but hope this helps someone else lost in the sauce.