iPhone:在与UIBarButtonItem一起使用FPPopover类时出错

Question

我使用的是FPPopover类，它为iPhones创建弹出窗口。我遵循了自述文件中的准确步骤，但我使用的不是xib文件中的UIbutton，而是以编程方式创建的UIBarButtonItem。但是，我得到了以下错误：

由于未识别的异常“NSInvalidArgumentException”终止应用程序，原因：'-UIBarButtonItem superview:未识别的选择器发送到实例0x6a3e420‘

我复制粘贴了与自述文件中相同的代码，但是我用(id )发件人更改了(UIButton*)okButton (id这里是UIBarButtonItem*)

-(void)popover:(id)sender
{
    //the view controller you want to present as popover
    TestClass *controller = [[TestClass alloc] init];
    //our popover
    FPPopoverController *popover = [[FPPopoverController alloc] initWithViewController:controller];
    //the popover will be presented from the okButton view
    [popover presentPopoverFromView:sender];
    //release
    [controller release];
}

我在想，也许这和UIBarButtonItem有关，而不是UIButton？或者是别的什么？我尝试将UIBarButtonItem转换为UIButton，但仍然给出了相同的错误。有什么解决办法吗？

还有一个注意事项，以防万一:这就是我如何编程地创建导航栏以及bar按钮的方式：

UINavigationBar *navBar = [[UINavigationBar alloc] initWithFrame:CGRectMake(320, 0, 320, 44)];
UINavigationItem *navItem = [[UINavigationItem alloc] initWithTitle:@"By Clubs"];
[navBar pushNavigationItem:navItem animated:NO];
UIBarButtonItem *editButton = [[UIBarButtonItem alloc] initWithTitle:@"Filter"
                                               style:UIBarButtonItemStyleBordered
                                              target:self
                                              action:@selector(popover:)];


navItem.rightBarButtonItem = editButton;

Answer 1

presentPopoverFromView只接受一个UIView子类。UIBarButtonItem不是UIView的子类，因此您需要找到与该按钮项相关的视图。这是我在FPPopoverController中使用的解决方案

    UIBarButtonItem *buttonItem = sender;
    UIView* btnView = [buttonItem valueForKey:@"view"];
    //On these cases is better to specify the arrow direction
    [popover setArrowDirection:FPPopoverArrowDirectionUp];
    [popover presentPopoverFromView:btnView];

这应该管用！让我知道！

Answer 2

这是b/c UIBarButtonItem从UIBarItem和NSObject继承的。只有从UIView继承的UI元素才具有superview属性。

Answer 3

我也犯了同样的错误。解决方案是以编程方式创建一个UIButton (在UIBar按钮项的同一位置--设置适当的坐标)，然后从UIButton中显示弹出。然后隐藏UIButton。

这段代码适用于我：

-(void)testMethod {

UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];

// set action as NULL if you dont need any method/functionality to call

[button addTarget:self action:@selector(aMethod)
 forControlEvents:UIControlEventTouchDown];


[button setTitle:@"Show View" forState:UIControlStateNormal];
button.frame = CGRectMake(130, -40, 160.0, 40.0);
[self.view addSubview:button];

AlertsViewController *controller = [[AlertsViewController alloc] init]; 

//our popover
FPPopoverController *popover = [[FPPopoverController alloc] initWithViewController:controller]; 

//the popover will be presented from the Button view 
[popover presentPopoverFromView:button]; 

//hide the button
button.hidden = YES;

}

-(void)aMethod {
// Write any functionality if you need
}

希望这能有所帮助。如果你有什么问题请告诉我。