ARC禁止显式发送“保留”消息

Question

I'm trying to use Amazon API for iOS that handles the login for Amazon website in Objective-C. I'm using this source . However, when I implement AMZNAuthorizeUserDelegate , I get the following error message:

ARC forbids explicit message send of 'retain'.

I've never used Objective-C before so I would appreciate if anyone could help me with the code.

Here is my code:

#import <LoginWithAmazon/LoginWithAmazon.h>
#import "AMZNAuthorizeUserDelegate.h"
#import "AMZNGetProfileDelegate.h"

@implementation AMZNAuthorizeUserDelegate

- (id)initWithParentController:(ViewController*)aViewController {
    if(self = [super init]) {
        parentViewController = [aViewController retain];
}

return self;
}

- (void)requestDidSucceed:(APIResult *)apiResult {
  AMZNGetProfileDelegate* delegate = [[[AMZNGetProfileDelegate alloc]         initWithParentController:parentViewController] autorelease];
[AIMobileLib getProfile:delegate];
}

- (void)requestDidFail:(APIError *)errorResponse {
NSString *message = errorResponse.error.message;
// Your code when the authorization fails.

[[[[UIAlertView alloc] initWithTitle:@"" message:[NSString
                                                      stringWithFormat:@"User authorization failed with message: %@",
                                                  errorResponse.error.message] delegate:nil
                   cancelButtonTitle:@"OK"otherButtonTitles:nil] autorelease] show];
}

@end

Answer 1

The error message is correct: the call to retain is no longer valid.

Automatic Reference Counting , or ARC, was added to the Objective-C language in 2011 with iOS 5 and Mac OS X 10.7. Prior to ARC, you had to manage the memory usage of your app manually with calls to methods such as -retain , -release , and -autorelease . ARC manages these calls automatically at compile time, and, as such, does not allow you to call them yourself.

As @Paulw11 mentions in his comment, you should be able to replace that line with

parentViewController = aViewController

and ARC will do the correct thing automatically.