CODEWITHSUNDEEP
iphoneiosxcodedelegates
cuda
cuda

Reputation: 13

wrong delegate declaration

Lets assume I have a class ClassA

header:

@interface ClassA : NSObject
- (id)initWithDelegate:(id)delegate;
@end

implementation:

@interface ClassA ()
{
    NSObject *_delegate;
}
@end

@implementation
- (id)initWithDelegate:(id)delegate
{
    self = [super init];
    if( self )
    {
        _delegate = delegate;
    }

    return self;
}
@end

Since I skipped the @property definition my delegate declaration defaults to strong? So this code is wrong because it will cause a leak, or does my delagate declaration default to weak?

Upvotes: 0

Views: 74

Answers (3)

DaGaMs
DaGaMs

Reputation: 1557

You are correct, this will cause ARC to retain the _delegate, ie make a "strong" reference. If you want to create a weak reference without declaring a @property, you can use

@interface ClassA ()
{
    __weak id _delegate;
}
@end

Upvotes: 0

Firoze Lafeer
Firoze Lafeer

Reputation: 17143

You do have to qualify that ivar as __weak. The default for an ivar is strong.

Otherwise, as you already know, you risk a retain cycle with delegates.

BTW, the convention here is 'id' rather than NSObject *.

Upvotes: 1

zoul
zoul

Reputation: 104065

It’s best to write the code in a way that makes this explicit:

@interface ClassA : NSObject
@property(weak) id delegate; // or @property(weak, readonly)
@end

@implementation ClassA

- (id)initWithDelegate: (id) delegate
{
    self = [super init];
    _delegate = delegate;
    return self;
}

@end

By default, you instance variable would be strong.

Upvotes: 0

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