Re: protocol and properties
Re: protocol and properties
- Subject: Re: protocol and properties
- From: Martin Hewitson <email@hidden>
- Date: Sun, 28 Nov 2010 10:15:55 +0100
It 'works' for me too, I just warnings from Xcode. Anyway, I'll check in case I made a typo or something.
Thanks!
Martin
On 28, Nov, 2010, at 9:50 AM, Stephen J. Butler wrote:
> On Sun, Nov 28, 2010 at 2:15 AM, Martin Hewitson
> <email@hidden> wrote:
>> Suppose I have a formal protocol which defines a method:
>>
>> - (NSArray*)objects;
>>
>> Then I implement a class which implements this protocol. To do that I make a property:
>>
>> @property (nonatomic, readwrite, retain) NSArray * objects;
>>
>> and put the appropriate synthesize statement in the implementation.
>>
>> I get compiler warnings that this class doesn't implement the protocol. It seems it doesn't take the synthesized getter as being an implementation of the -objects method.
>>
>> I also tried explicitly adding the implementation, but the warning remains:
>>
>> - (NSArray*) objects
>> {
>> return objects;
>> }
>>
>> Am I doing something wrong here, or is it not possible to use a property to satisfy a protocol?
>
> Works for me:
>
>
> #import <Foundation/Foundation.h>
>
> @protocol Bar
> - (NSArray*) objects;
> @end
>
> @interface Foo : NSObject < Bar > {
> NSArray *objects;
> }
> @property (nonatomic, readwrite, retain) NSArray *objects;
> @end
>
> @implementation Foo
> #if 0
> - (NSArray*) objects { return objects; }
> - (void) setObjects:(NSArray*)o {
> [o retain];
> [objects autorelease];
> objects = o;
> }
> #else
> @synthesize objects;
> #endif
> @end
>
> int main (int argc, const char * argv[]) {
> NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
>
> Foo *f = [[[Foo alloc] init] autorelease];
> id< Bar > b = f;
>
> f.objects = [NSArray arrayWithObjects:@"one",
> @"two", @"three", nil];
> NSLog( @"objects = %@", [b objects] );
>
> [pool drain];
> return 0;
> }
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Hewitson
Albert-Einstein-Institut
Max-Planck-Institut fuer
Gravitationsphysik und Universitaet Hannover
Callinstr. 38, 30167 Hannover, Germany
Tel: +49-511-762-17121, Fax: +49-511-762-5861
E-Mail: email@hidden
WWW: http://www.aei.mpg.de/~hewitson
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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