在iOS9中不推荐使用NSURLConnection

Question

I want to download a file with a NSURLRequest and save it but in the line with the

NSData * data = ... happens an error.

NSURL *Urlstring = [NSURL URLWithString:@"http://yourdomain.com/yourfile.pdf"];
NSURLRequest *request = [NSURLRequest requestWithURL: Urlstring];
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

NSURL *documentsURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
documentsURL = [documentsURL URLByAppendingPathComponent:@"localFile.pdf"];

[data writeToURL:documentsURL atomically:YES];

The warning Message is that i should use NSURLSession dataTaskwithrequest "because sendSynchronousRequest is deprecated in iOS 9 but that doesn't work I hope someone can help me

Answer 1

Now you have to use NSURLSession

Example (GET):

-(void)placeGetRequest:(NSString *)action withHandler:(void (^)(NSData *data, NSURLResponse *response, NSError *error))ourBlock {

    NSString *urlString = [NSString stringWithFormat:@"%@/%@", URL_API, action];


    NSURL *url = [NSURL URLWithString:urlString];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];

    [[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:ourBlock] resume];
}

Now you will need to call that method with an action (or your full URL if you prefer) and the block that will be executed when the API call return.

[self placeGetRequest:@"action" withHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    // your code
}];

Inside that block, you will received a NSData with the response data and NSURLResponse with the HTTP response. So now, you can put your code there:

NSURL *documentsURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
documentsURL = [documentsURL URLByAppendingPathComponent:@"localFile.pdf"];

[data writeToURL:documentsURL atomically:YES];

Main difference between NSURLSession and NSURLConnection

• NSURLConnection: if we have an open connection with NSURLConnection and the system interrupt our App, when our App goes to background mode, everything we have received or sent were lost.

• NSURLSession: solve this problem and also give us out of process downloads. It manage the connection process even when we don't have access. You will need to use application:handleEventsForBackgroundURLSession:completionHandler in your AppDelegate

So with the use of NSURLSession, you don't need to manage or to check your internet connection because OS does it for you.