int i = 0;
while (YES) {
    @autoreleasepool {
        NSString *string = [[NSString alloc] initWithFormat:@"%d", i];
        // or
        // NSString *string = [[NSString alloc] init];

        [[string rac_willDeallocSignal] subscribeCompleted:^{
            NSLog(@"obj dealloc");
        }];
    }
    i++;
}