CODEWITHSUNDEEP
iphoneobjective-cautomatic-ref-counting
Shamsudheen TK
Shamsudheen TK

Reputation: 31311

ARC Converted Application Issue: passing adress of non local object to _autoreleaseing parameter for write-back

I'm trying to make app with ios5 and i'm really confused why happen this. Could someone help me an explain me why have error in lines when appear &error

Passing address of non-local object to __autoreleasing parameter for write-back

The below call cause the error

// note the following method returns _inStream and _outStream with a retain count that the caller must eventually release

if (![netService getInputStream:&_inStream outputStream:&_outStream]) {

 NSLog(@"error in get input and output streams");
 return;
}

my class .h

NSInputStream      *_inStream;
NSOutputStream     *_outStream;

@property (nonatomic, strong) NSInputStream *_inStream;    
@property (nonatomic, strong) NSOutputStream *_outStream;

my class .m

@synthesize _inStream;
@synthesize _outStream;

The getInputStream is a NSNetService class method

Please the NSNetService class getInputStream implementation below

/* Retrieves streams from the NSNetService instance. The instance's delegate methods are not called. Returns YES if the streams requested are created successfully. Returns NO if or any reason the stream could not be created. If only one stream is desired, pass NULL for the address of the other stream. The streams that are created are not open, and are not scheduled in any run loop for any mode.
*/
- (BOOL)getInputStream:(NSInputStream **)inputStream outputStream:(NSOutputStream **)outputStream;

I have found the related posts in

non-local-object-to-autoreleasing-parameter

-pointer-ownership-issues

non-local-object-to-autoreleasing

from-ios-4-to-ios-5arc-passing-address

However i'm unable to found the issue

Any help on this issue is appreciated

Thanks

Upvotes: 2

Views: 4197

Answers (2)

Shamsudheen TK
Shamsudheen TK

Reputation: 31311

I have found the solution

Here we go. Create the variables as local and assign them back to the original. Thanks to @borreden for the insightful info.

Here is my latest code.

NSInputStream  *tempInput  = nil;
NSOutputStream *tempOutput = nil;

// note the following method returns _inStream and _outStream with a retain count that the caller must eventually release
if (![netService getInputStream:&tempInput outputStream:&tempOutput]) {

    NSLog(@"error in get input and output streams");
    return;
}
_inStream  = tempInput;
_outStream = tempOutput;

Upvotes: 6

user387184
user387184

Reputation: 11053

The reason is that you can't pass your _inStream and _outStream like this when using ARC. (since you are using ARC in the converted version)

Since if these variables are overwritten within the method they would leak.

You need to change you handle the return value (if it changes at all) or just pass as a normal parameter.

There is no explicit memory management with retain/release anymore so ARC can not handle this case automatically.

Upvotes: 0

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