How to get an array from NSMutableData - objective-c

Question

I have text file with 5 strings. I need to use NSURLConnection to get contnent of this file. But NSLog shows me, that 'dump' is empty. How can I transform the data from NSMutableData to NSArray. Arrays is because I need to show those 5 items in a TableView.
NSURLRequest *theRequest=[NSURLRequest
requestWithURL:[NSURL URLWithString:#"http://dl.dropbox.com/u/25105800/names.txt"]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection) {
receivedData = [NSMutableData data];
NSString *dump = [[NSString alloc] initWithData:receivedData
encoding:NSUTF8StringEncoding];
NSLog(#"data: %#", dump);
NSArray *outputArray=[dump componentsSeparatedByString:#"\n"];
self.namesArray = outputArray;
Thanks in advance. BTW URL works, you can see the file.

Answer 1

Here's how you implement this solution with a delegate:
In your .h file:
#interface MyClass : NSObject <NSURLConnectionDelegate, NSURLConnectionDataDelegate>
#property (nonatomic, retain) NSMutableData *receivedData;
#property (nonatomic, retain) NSArray *namesArray;
#end
In you .m file:
#implementation MyClass
#synthesize receivedData = _receivedData;
#synthesize namesArray = _namesArray;
- (id)init {
self = [super init];
if (self) {
self.receivedData = [NSMutableData data];
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://dl.dropbox.com/u/25105800/names.txt"] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
[connection start];
}
return self;
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
NSLog(#"Received response! %#", response);
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[self.receivedData appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSString *dump = [[NSString alloc] initWithData:self.receivedData encoding:NSUTF8StringEncoding];
NSLog(#"data: %#", dump);
self.namesArray = [dump componentsSeparatedByString:#"\n"];
}
#end

Answer 2

If you don't want to use a delegate, you can use a synchronous call with NSURLConnection, like this:
NSURLRequest *theRequest=[NSURLRequest
requestWithURL:[NSURL URLWithString:#"http://dl.dropbox.com/u/25105800/names.txt"]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
NSError *error = nil;
NSHTTPURLResponse *response = nil;
NSData *receivedData = [NSURLConnection sendSynchronousRequest:theRequest response:&response error:&error];
if (error == nil) {
NSString *dump = [[NSString alloc] initWithData:receivedData
encoding:NSUTF8StringEncoding];
NSLog(#"data: %#", dump);
NSArray *outputArray=[dump componentsSeparatedByString:#"\n"];
self.namesArray = outputArray;
}
Just beware that this will not be running asynchronously. If you don't want it to run on the main thread and block your main thread/UI, consider using a separate thread to execute that code or use GCD.

Answer 3

You have to use the delegate, then save the received data into receivedData (which is of course empty right now.. you just initalized it.) and then you transform the data into a string, like you did it in your example. Have a look at NSURLConnectionDelegate

Answer 4

You need to implement the delegate methods for NSURLConnection to be notified of incoming data. You are using the asynchronous methods.
Also note that [NSMutableData data] just creates an empty data-object.. so you can't expect it to contain any data..
I suggest you read https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html#//apple_ref/doc/uid/20001836-BAJEAIEE
(completely!)