UIBarButtonItem自定義（修改與左端的距離）

//傳回

    UIButton *leftButton = [UIButton buttonWithType:UIButtonTypeCustom];

    leftButton.frame = CGRectMake(0, 0, 40, 44);

    [leftButton setBackgroundImage:[UIImage imageNamed:@"fanhui1"] forState:UIControlStateNormal];

    [leftButton addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];

    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithCustomView:leftButton];

    UIBarButtonItem *spaceItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];

    spaceItem.width = - 15;

    self.navigationItem.leftBarButtonItems = @[spaceItem, leftItem];