properties are strong by default now.

main.m

//
//  main.m
//  testproperties
//
//  Created by Nicolas Bouilleaud on 15/03/12.
//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <objc/runtime.h>


@interface TestProp : NSObject
@property id defaultObject;
@property (nonatomic) id nonatomicObject;
@property (strong) id strongObject;
@property (weak) id weakObject;
@property (assign) id assignObject;
@end

@implementation TestProp
@synthesize defaultObject,nonatomicObject,strongObject,weakObject,assignObject;
@end

int main(int argc, const char * argv[])
{
    id TestPropClass = objc_getClass("TestProp");
    unsigned int outCount, i;
    objc_property_t *properties = class_copyPropertyList(TestPropClass, &outCount);
    for (i = 0; i < outCount; i++) {
        objc_property_t property = properties[i];
        NSLog(@"%s: %s\n", property_getName(property), property_getAttributes(property));
    }

    return 0;
}

output

2012-03-15 15:08:32.138 testproperties[304:403] defaultObject T@,&,VdefaultObject
2012-03-15 15:08:35.505 testproperties[304:403] nonatomicObject T@,&,N,VnonatomicObject
2012-03-15 15:08:36.608 testproperties[304:403] strongObject T@,&,VstrongObject
2012-03-15 15:08:38.385 testproperties[304:403] weakObject T@,W,VweakObject
2012-03-15 15:08:39.611 testproperties[304:403] assignObject T@,VassignObject