CODEWITHSUNDEEP
objective-ciosnsarraynsmutabledata
Reshat Belyalov
Reshat Belyalov

Reputation: 973

How to get an array from NSMutableData

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.

Upvotes: 1

Views: 1813

Answers (4)

Simon Germain
Simon Germain

Reputation: 6844

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

Upvotes: 2

Simon Germain
Simon Germain

Reputation: 6844

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.

Upvotes: 1

Martin Ullrich
Martin Ullrich

Reputation: 100581

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!)

Upvotes: 0

calimarkus
calimarkus

Reputation: 9977

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

Upvotes: 0

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