CopyPropertyDoesNotReturnCopy.m

#import <Foundation/Foundation.h>

@interface ArrayReturner : NSObject

@property (copy, nonatomic) NSArray * array;

@end

@implementation ArrayReturner
{
    NSMutableArray * _array;
}

- (BOOL)myArrayIsIdenticalTo:(NSArray *)otherArray
{
    return _array == otherArray;
}

@end

int main(int argc, const char *argv[])
{
    @autoreleasepool {
        
        ArrayReturner * a = [ArrayReturner new];
        [a setArray:@[@1, @2]];
        NSArray * returnedArray = [a array];
        // Does not throw
        NSCAssert([a myArrayIsIdenticalTo:returnedArray],
                  @"Returned array is a separate instance.");
    }
    
    return 0;
}