objective c - ARC forbids explicit message send of 'retain' issue

Question

I'm using this very simple code from the Apple Guide:

NSMutableData *receivedData;

// Create the request.
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.apple.com/"]
                        cachePolicy:NSURLRequestUseProtocolCachePolicy
                    timeoutInterval:60.0];
// create the connection with the request
// and start loading the data
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.
}

But for the line receivedData = [[NSMutableData data] retain]; Xcode gives me an error: PushController.m:72:25: ARC forbids explicit message send of 'retain'

How to deal with it? I'm using the Xcode 4.4.1

Answer 1

You are currently using the ARC to reference count for you. (ARC is "Automatic Reference Counting", a new feature to iOS 5). Therefore you do not need to manually retain or release. You can either remove your retain calls all together or turn off ARC by doing the following:

Click on the name of the project on the navigation view in the left side, go to Targets -> Build Phases and add -fno-objc-arc to the "compiler flags" for any relevant files.

See here for info on removing.

See here for basic info on ARC.