How to use the NSUrlConnection for getting the data from web?

问题

In my application I want to use the NSURLConnection class. So please tell me how to use this one? This contain the lot of delegate methods, please tell me how to use them?

回答1:

Initiate the connection using

self.responseData = [NSMutableData data];
NSURL *url = [NSURL URLWithString:@"http://sampleurl/"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection autorelease];

and you can catch the response in the connectionDidFinishLoading delegate method

#pragma mark - NSURLConnection Delegate Methods

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [self.responseData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.responseData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"Connection failed: %@", [error description]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
        //Getting your response string
    NSString *responseString = [[NSString alloc] initWithData:self.responseData encoding:NSUTF8StringEncoding];
self.responseData = nil;
    }

For your memory leak problem

Declare the response data in interface file

NSMutableData *_responseData;

with property as below

@property (nonatomic, retain) NSMutableData *responseData;

and synthesize it

@synthesize responseData = _responseData;

Dont release it anywhere (We have used convenient constructors for allocation). We have already set it to nil in connectionDidFinishLoading method.

回答2:

In iOS 5 and OS X 10.7 or later you can load data asynchronously using the following:

NSURL *url = [NSURL URLWithString:@"http://sampleurl/"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue currentQueue]
       completionHandler: ^(NSURLResponse * response, NSData * data, NSError * error) {
           NSHTTPURLResponse * httpResponse = (NSHTTPURLResponse*)response;
           if(httpResponse.statusCode == 200) {
               //your code to handle the data
           }
       }
];

Or if you want to do it synchronously (not recommended if you are loading large data as it will hang the application) (available in OS X 10.2+ and iOS 2.0+)

NSURL *url = [NSURL URLWithString:@"http://sampleurl/"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
NSURLResponse * response;
NSError * error;
NSData * data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

来源：https://stackoverflow.com/questions/7483085/how-to-use-the-nsurlconnection-for-getting-the-data-from-web

标签

objective-c

nsurlconnection