关于手机自带照相机内存泄露的问题

我在调用手机自带相机的时候出现了内存泄露，代码如下

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.allowsEditing = NO;
    if (sender.tag == 1)
    {
        [imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
    }
    else
    {
        [imagePicker setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
    }
    [imagePicker setDelegate:self];
        NSLog(@"picker retaincount1 %i",[imagePicker retainCount]);
    [self presentModalViewController:imagePicker animated:YES];
        NSLog(@"picker retaincount2 %i",[imagePicker retainCount]);
控制台输出的是

picker retaincount1 1
picker retaincount2 4

怎么变成4了呢？求大神解决