Question

我正在开发一个可以在iPhone上运行的应用程序，但是运行正常，但是当我尝试在iPad上运行时会崩溃

这是我的代码：

- (void)parseCountryStates:(NSDictionary *)json
{    
    countryPickerView.hidden = TRUE;
    NSDictionary *listing = [json objectForKey:@"country"];
    countryArray = [listing allValues];
    countryIDArray = [listing allKeys];

    [countryPickerView reloadAllComponents];
    alertController = [UIAlertController
                       alertControllerWithTitle:@"Select Service Type"
                       message:nil
                       preferredStyle:UIAlertControllerStyleActionSheet];
    int count = (int)[countryPickerView numberOfRowsInComponent:0];

    for (int i = 0; i < count; i++)
    {
        UIAlertAction* button = [UIAlertAction
                                 actionWithTitle:[[countryPickerView delegate] pickerView:countryPickerView titleForRow:i forComponent:0]
                                 style:UIAlertActionStyleDefault
                                 handler:^(UIAlertAction * action)
                                 {
                                     countryField.text = [action title];
                                     countryStr = countryField.text;
                                     if ([countryArray containsObject:countryStr]) {
                                         countryidStr = [countryIDArray objectAtIndex:[countryArray indexOfObject:countryStr]];
                                         NSLog(@"CountryidStr %@",countryidStr);
                                         [self getState];
                                     }
                                 }];
        [alertController addAction:button];

    }

    UIAlertAction* cancel = [UIAlertAction
                             actionWithTitle:@"Cancel"
                             style:UIAlertActionStyleCancel
                             handler:^(UIAlertAction * action)
                             {
                                 //  UIAlertController will automatically dismiss the view
                             }];
    [alertController addAction:cancel];
    [self presentViewController:alertController animated:true completion:nil];
}

我正在共享它的崩溃日志

***由于未捕获的异常'NSGenericException'而终止应用程序，原因：'您的应用程序呈现了一个UIAlertController（）样式UIAlertControllerStyleActionSheet。的modalPresentationStyle 具有这种样式的UIAlertController是UIModalPresentationPopover。您必须通过警报提供此弹出窗口的位置信息控制器的popoverPresentationController。您必须提供 sourceView和sourceRect或barButtonItem。如果此信息是当您提出警报控制器时不知道，您可以在 UIPopoverPresentationControllerDelegate方法 -prepareForPopoverPresentation。

Answer 1

实际上不允许在iPad上使用Alertcontrollers，而是可以使用弹出窗口来显示某种警报

以编程方式

UIViewController *newViewCont = [[UIViewController  alloc] init];
newViewCont.view = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 180, 180)];
newViewCont.modalPresentationStyle = UIModalPresentationPopover;

[self presentViewController:newViewCont animated:YES completion:nil];

UIPopoverPresentationController *pop = [newViewCont popoverPresentationController];
pop.permittedArrowDirections = UIPopoverArrowDirectionAny;

[pop setSourceView:myButton];
[pop setSourceRect:myButton.bounds];

使用情节提要

// grab the view controller we want to show
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
UIViewController *controller = [storyboard instantiateViewControllerWithIdentifier:@"Pop"];

// present the controller
// on iPad, this will be a Popover
// on iPhone, this will be an action sheet
controller.modalPresentationStyle = UIModalPresentationPopover;
[self presentViewController:controller animated:YES completion:nil];

// configure the Popover presentation controller
UIPopoverPresentationController *popController = [controller popoverPresentationController];
popController.permittedArrowDirections = UIPopoverArrowDirectionUp;
popController.delegate = self;

// in case we don't have a bar button as reference
popController.sourceView = self.view;
popController.sourceRect = CGRectMake(30, 50, 10, 10);

关闭弹出窗口

[self dismissViewControllerAnimated:YES completion:nil];

有一个称为UIPopoverPresentationControllerDelegate的新协议，在由于旋转或界面变化而解雇和位置变化时会被调用。如果我们愿意，我们甚至可以阻止Popover被解雇。这是我们可以实现的三种方法：

- (void)popoverPresentationControllerDidDismissPopover:(UIPopoverPresentationController *)popoverPresentationController {

// called when a Popover is dismissed
}

- (BOOL)popoverPresentationControllerShouldDismissPopover:(UIPopoverPresentationController *)popoverPresentationController {

// return YES if the Popover should be dismissed
// return NO if the Popover should not be dismissed
return YES;
}

- (void)popoverPresentationController:(UIPopoverPresentationController *)popoverPresentationController willRepositionPopoverToRect:(inout CGRect *)rect inView:(inout UIView *__autoreleasing  _Nonnull *)view {

// called when the Popover changes position
}

别忘了遵守协议，并将委托设置为您的反应班。

Answer 2

将源代码视图和源代码rect添加到您的alertController。

[[alertController popoverPresentationController] setSourceView:self.view];
[[alertController popoverPresentationController] setSourceRect:CGRectMake(0,0,1,1)];
[[alertController popoverPresentationController] setPermittedArrowDirections:UIPopoverArrowDirectionUp];

[self presentViewController:alertController animated:true completion:nil];

Answer 3

在iPad上不允许使用UIPopovers，但是您可以按照其他答案的指示进行操作。这是Swift 5.x版本。

let ac = UIAlertController(title: "Some title goes here", message: nil, preferredStyle: .actionSheet)

ac.addAction(UIAlertAction(title: "Some button name", style: .default) {
        [unowned self] _ in
        // stuff to do goes here
        self.doSomething()
    })

// iPad specific code
ac.popoverPresentationController?.sourceView = self.view
let xOrigin = nil // Replace this with one of the lines at the end
let popoverRect = CGRect(x: xOrigin, y: 0, width: 1, height: 1)
ac.popoverPresentationController?.sourceRect = popoverRect
ac.popoverPresentationController?.permittedArrowDirections = .up

present(ac, animated: true)

将let xOrigin = nil行替换为下面的一行之一将控制弹出窗口在导航栏下方的显示位置。如果您将控件控制在iPad导航栏下方，则还可以在其他元素的边界或框中将x和y更改为适当的值。

左上方

 let xOrigin = 0

中上层

let xOrigin = self.view.bounds.width / 2

右上方

let xOrigin = self.view.bounds.width

希望这会有所帮助。

未捕获的异常'NSGenericException：应用程序提供了一个UIAlertControllerStyleActionSheet

3 个答案: