关于NSString，retainCount为－1

NSString *test1 = [[NSString alloc] initWithString:@"one"];

    NSLog(@"test1 .......%ld",(unsigned long)[test1 retainCount]);

           

NSString *test2 = [[NSString alloc] initWithFormat:@"one%d",1];
    
    NSLog(@"test2 .......%ld", (unsigned long)[test2 retainCount]);
           

NSString *test3 = [NSString stringWithString:@"one"];
    NSString *test4 = [NSString stringWithString:[NSString stringWithFormat:@"test,%d",1]];
    
    NSLog(@"test3 .......%ld",(unsigned long)[test3 retainCount]);
    NSLog(@"test4 .......%ld",(unsigned long)[test4 retainCount]);
           

结果：