如何为NSURLConnection定义NSMutableData实例？

Question

From https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html#//apple_ref/doc/uid/20001836-BAJEAIEE

NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection) {
    // Create the NSMutableData to hold the received data.
    // receivedData is an instance variable declared elsewhere.
    receivedData = [[NSMutableData data] retain];
} else {
    // Inform the user that the connection failed.
}

I'm a relatively new iOS6 programmer. First off, I think that with ARC it should be just receivedData = [NSMutableData data] ?

Secondly, how should I declare the receivedData instance variable? I'm guessing @property (strong, nonatomic) NSMutableData *receivedData; in the header and @synthesize receivedData in the implementation.

However, I'm still trying to grok multithreading and ARC in iOS6. Should the property declaration be

@property (strong, nonatomic) NSMutableData *receivedData;

or just

@property (strong) NSMutableData *receivedData;

for the received data in the delegate of an asynchronous NSURLConnection?

Answer 1

You should implement the remain methods of the NSURLConnectionDelegate . That's where you will get the data. If you want to use blocks, for instance, you can use this . Atomic guarantees that even if multiple threads are accessing the ivar and changing it, a value will be always be there. You get some boost if you have it as nonatomic . Your application logic should be responsible for data integrity and not how a setter/getter are synthesised. So in general, should be nonatomic .

First off, I think that with ARC it should be just receivedData = [NSMutableData data] ?

Yes, its enough.