将左侧按钮和自定义标题添加到iOS中的导航栏

Question

我使用以下代码将自定义标题和左键按钮添加到导航栏： -

    UIBarButtonItem *button1 =[[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"img1.png"] style:UIBarButtonItemStylePlain target:self action:@selector(popBack)];
    UIBarButtonItem *button2 =[[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"img2.png"] style:UIBarButtonItemStylePlain target:self action:nil];
    self.navigationItem.leftBarButtonItems = [[NSArray alloc] initWith:button1, button2, nil];

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 360, 30)];     
    [label setFont:[UIFont fontWithName:@"Arial-BoldMT" size:14]];                 
    [label setBackgroundColor:[UIColor clearColor]];
    [label setTextColor:[UIColor whiteColor]];
    [label setText:@"Detail Controller"];                                                      
    label.textAlignment = UITextAlignmentCenter;  //NSTextAlignmentCenter
    self.navigationItem.titleView=label;

此处，左侧栏按钮未正确放置且标题对齐未正确（左侧栏按钮正在将标题推到导航栏的右侧）。