如何从nsmutabledata获取数组

Question

我有5个字符串的文本文件。我需要使用nsurlconnection获取此文件的循环。但NSLog向我展示，“转储”是空的。如何将来自NSMutableData的数据转换为NSArray。阵列是因为我需要在TableView中显示这些5个项目。

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;

.

提前感谢。BTW URL工作，您可以看到文件。

Answer 1

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 2

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 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!)