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iOS Download and Save plist file, please help me

M

MynEz

macrumors newbie
Original poster
Jan 13, 2011
13
0
Regina,Sask
Hi, agian

I don't know the correct way to do with this url: http://plistupdate.transitlive.com/saturday-1299867550.plist

I'm now writing a project about to download this data and show in the tableView. I want to load this data and save in my directory but it seems that when I access to this url, it's not automatically file for download. So I did try to parse the elements from this data by using NSXMLParser but I couldn't because the key of element in each row has the same name. I don't know the correct way to do with this. If somebody knows or can give me the advice please help.
 
Download the file to your sandbox using NSURLConnection. Then open the file using whichever class is the root object in the plist (usually NSArray or NSDicationary).
 
PhoneyDeveloper said:
Download the file to your sandbox using NSURLConnection. Then open the file using whichever class is the root object in the plist (usually NSArray or NSDicationary).
Click to expand...

Couldn't you also just read it in with initWithContentsOfURL: and save it locally with writeToFile:atomically: ?

B
 
balamw said:
Couldn't you also just read it in with initWithContentsOfURL: and save it locally with writeToFile:atomically: ?

B
Click to expand...

You could do but that method is synchronous. With a NSURLConnection you can download asynchronously (without having to thread the download yourself) which is normally better for the user experience.
 
robbieduncan said:
You could do but that method is synchronous. With a NSURLConnection you can download asynchronously (without having to thread the download yourself) which is normally better for the user experience.
Click to expand...

OK. So that's basically like running wget or curl as background thread and then acting on the local copy. Makes sense.

The impact on UX then ultimately depends somewhat on the size of the plist and the bandwidth and latency of the pipe available at the time?

B
 
The timeout for networking is apparently longer than the watchdog kill time. You will be killed sooner or later if you use synchronous networking because of this.
 
Well, thank you for you reply.
Now I'm using the NSURLConnection and request to this url, it seems like the processing time to parse this data took so long. Do you have any idea? I created the dictionary at <plist> and try to run in console but i couldn't display all of these objects into the table view. If you can help me fix about my code, I'll be glad. Thank you

This is my code:
Code: 
NSMutableArray = list;

-(void)viewDidLoad{
	
	[list removeAllObjects];
	[[self tableView]reloadData];
	NSURL *url = [NSURL URLWithString:@"http://plistupdate.transitlive.com/saturday-1299867550.plist"];
	NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:30];
	if (connection) {
		[connection cancel];
		[connection release];
	}
	[xmlData release];
	xmlData = [[NSMutableData alloc]init];
	connection = [[NSURLConnection alloc]initWithRequest:request delegate:self startImmediately:YES];
	[super viewDidLoad];
}


- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
	if ([elementName isEqual:@"plist"]) {
		NSLog(@"Found plist file!");
		datas = [[NSDictionary alloc]init];
		titleString = [[NSMutableString alloc]init ];
	}
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
	if ([elementName isEqual:@"plist"]) {
		NSLog(@"ended title: %@", titleString); 
		[list addObject:datas];
		[titleString release];
		titleString = nil;
	}
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
	[titleString appendString:string];
}
 
Do this after you've saved the file in your sandbox.

Code: 
NSString* path = path to the file;
NSArray* array = [NSArray arrayWithContentsOfFile:path];

It will parse the file for you. (If the root is a dictionary use [NSDictionary dictionaryWithContentsOfFile:])
 
Err... I'm just beginner could you show me how to start and save file? and do I need to forget about the parser?

Thank you
 
Yes, forget about the parser. Just use the code I showed. How do you create this plist file?

To use the NSURLConnection to save the file there are a million tutorials and links and posts on this forum and every other forum. You just have to implement a few delegate callbacks that the NSURLConnection makes to its delegate. Save the file in each callback. When it's finished then open the file with the code I showed.
 
Yes, this plist file is from my instructor. well I loaded the data from url and saved it, last night I ran the program and everything went well but this morning I tried to run it agian but it got crashed. Do you have any ideas, here is my code, please help.
Code: 
 //Save
NSString *urlString = @"http://plistupdate.transitlive.com/weekday-1299867550.plist";
	NSURL *url = [NSURL URLWithString:urlString];
	NSData *datas = [NSData dataWithContentsOfURL:url];
	NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
	NSString *documentsDirectory = [paths objectAtIndex:0];
	NSString *plistFile = [documentsDirectory stringByAppendingPathComponent:@"abc.plist"];
	
	[datas writeToFile:plistFile atomically:YES];

Load

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
		
		NSString *documentsDirectory = [paths objectAtIndex:0];
		
		NSString *plistPath = [documentsDirectory stringByAppendingPathComponent:@"abc.plist"];
		if (plistPath) {
			NSLog(@"pass!");
		}
		NSDictionary *dict = [[NSDictionary alloc]initWithContentsOfFile:plistPath];
		self.dataUpdate = dict;
		[dict release];
		if (dict) {
			NSLog(@"has file");
		}
 
It's probably from NSData. I used NSLog to check it but It couldn't retrieve the data from url. So I don't know how to fix it please help.:(
 
MynEz said:
It's probably from NSData. I used NSLog to check it but It couldn't retrieve the data from url.
Click to expand...
It's probably? I think you should find out for sure. I would suggest putting a breakpoint in before the section of code you suspect and step through it line by line until you find the problem line. Basic debugging is a key skill; no time like the present to learn more about it. :)
 
That file is 10MB. Kind of a big plist file. It takes Safari a minute to download it on my Mac.

You can't possibly download it using NSData dataWithContentsOfURL: on the main thread.

If you were running the app in the Sim it could do this because the watchdog isn't active, but your app would be frozen for a minute or more. On a device your app would be killed by the watchdog.

Also, it's possible that you don't have 10MB free memory on an older device, which could also cause problems.

You need to download the file using NSURLConnection and its asynchronous method. The root of the plist is a dictionary so once it's a local file you can open it with NSDictionary dictionaryWithContentsOfFile: but it might take some seconds to open.
 
Thanks to you guys, I used breakpoint to check it and as you said the file size is big so it's quit itself. I'm gonna try with NSURLConnection. Is it really good for reducing the processing time?
 
MynEz said:
Thanks to you guys, I used breakpoint to check it and as you said the file size is big so it's quit itself. I'm gonna try with NSURLConnection. Is it really good for reducing the processing time?
Click to expand...

It won't make the download run any faster but, assuming you use the asynchronous methods, it will not cause the main runloop thread to stop which will mean your app won't get killed.
 
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