Question

我有一个导航栏，其中包含一个导航项，其中包含2个栏按钮，这些是在故事板中创建的，我想在运行时更改其中一个按钮，现在可以正常工作：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    UINavigationItem *thisNavBar = [self myNavigationItem];
    thisNavBar.rightBarButtonItem = nil; // this works, it gets removed

    UIBarButtonItem *insertBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemEdit target:self action:@selector(insertSkemaItem:)];

    thisNavBar.rightBarButtonItem = insertBtn; // this also works, it sets the btn

}

现在，在另一个由另一个控制器调用的方法中，它不起作用

- (void)callChildChange { 

    ...

    // remove old btn
    UINavigationItem *thisNavBar = [self skemaNavigationItem];
    thisNavBar.rightBarButtonItem = nil; // does not work?
}

该方法没有任何问题，它运行得很好，但nav btn项目没有被删除？

skemaNavigationItem是一个导航项，在.h文件中声明，它链接我通过故事板制作的导航项。

Answer 1

您的UI项目需要在头文件（.h）中添加到您的代码中（通过ctrl-dragging），以便可以从其他类/视图控制器公开访问它们。

假设您已完成此操作，最好使用

隐藏UI项目

relevantClass.yourViewObject.hidden = YES;

或者如果你真的需要将其删除，

[relevantClass.yourViewObject.view removeFromSuperView];

<强>编辑

更改目标方法的选项：

声明@property (nonatomic, assign) BOOL myButtonWasPressed;和：

 - (IBAction) myButtonPressed
 {
     if (!self.myButtonWasPressed)
     {
         // This code will run the first time the button is pressed
         self.myButton.text = @"New Button Text";
         self.myButtonWasPressed = YES;
     } 
      else
          {
             // This code will run after the first time your button is pressed
             // You can even set your BOOL property back, and make it toggleable
          }

 }

或

- (IBAction) myButtonWasPressedFirstTime 
 {    
  // do what you need to when button is pressed then...

   self.myButton.text = @"New Button Text";    

   [self.myButton removeTarget:self action:@selector(myButtonPressedFirstTime) forControlEvents:UIControlEventTouchUpInside];

   [self.myButton addTarget:self action:@selector(myButtonPressedAgain) forControlEvents: UIControlEventTouchUpInside]; 

 }

- (IBAction) myButtonWasPressedAgain
{
   // this code will run the subsequent times your button is pressed
}

UINavigationItem在运行时更改属性的问题

1 个答案: