iphone - UIBarButtonItem 不显示图像

Question

我的导航栏有问题。问题是我试图覆盖 NavigationBar 从超级 viewController 拥有的 LeftBarButtonItem，如下所示：

“超级视图控制器”

UIImageView *logoApp = [[UIImageView alloc] initWithImage:[UIImageimageNamed:@"logo.png"]];
[logoApp setFrame:CGRectMake(5, 5, 55, 30)];
UIBarButtonItem *containingLogoApp = [[UIBarButtonItem alloc] initWithCustomView:logoApp];
self.navigationItem.leftBarButtonItem = containingLogoApp;

现在我试图在不同的 viewControllerB 中覆盖它，如下所示：

UIImageView *backImg = [[UIImageView alloc] initWithImage:[UIImageimageNamed:@"back.png"]]; 
[logoApp setFrame:CGRectMake(5, 5, 17, 22)];
UIBarButtonItem *containingBackButton = [[UIBarButtonItem alloc]initWithCustomView:backImg]; 
self.navigationItem.leftBarButtonItem = containingBackButton;

这是相同的代码，并且仅在应用程序第一次运行时才有效。如果我第二次运行它，它不再显示分配的图像ViewControllerB。这发生在我项目中的每个图像上，它仅在我第一次在模拟器上运行应用程序时才有效，在第一次运行之后......就像什么都没发生一样。

如何覆盖 leftBarButtonItem？

Answer 1

试试这个代码

UIBarButtonItem *backButton = [[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"dynamic_blue_left.png"] style:UIBarButtonItemStyleBordered target:self action:@selector(rightSwipeClicked:)];
self.navigationItem.leftBarButtonItem = backButton;

它工作正常..可能对你有用

Answer 2

UIButton *backButton =  [UIButton buttonWithType:UIButtonTypeCustom];
[backButton setImage:[UIImage imageNamed:@"back.png"] forState:UIControlStateNormal];
[backButton addTarget:self action:@selector(backAction) forControlEvents:UIControlEventTouchUpInside];
[backButton setFrame:CGRectMake(0, 0, 50, 30)];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];