Swift UIAlertController-> ActionSheet iPad iOS8崩溃

Question

目前，我的ActionSheet遇到了大麻烦。在iPhone上效果很好，但在iPad上只会崩溃

我只用一个按钮创建一个新项目

import UIKit

extension ViewController : UIActionSheetDelegate {

    func actionSheet(actionSheet: UIActionSheet, didDismissWithButtonIndex buttonIndex: Int) {

        if actionSheet.tag == 0 {
            if buttonIndex == 1 {
                // doing something for "product page"
            } else if (buttonIndex == 2) {
                // doing something for "video"
            }
        }
    }

}

class ViewController: UIViewController, UIActionSheetDelegate {
    @IBAction func test(sender: AnyObject) {

        let systemVersion: NSInteger = (UIDevice.currentDevice().systemVersion as NSString).integerValue
        if systemVersion < 8 {
            // iOS7:
            let action:UIActionSheet = UIActionSheet(title: "Change Map Type", delegate: self, cancelButtonTitle: "Back", destructiveButtonTitle: nil, otherButtonTitles: "Product Page", "Video")
            action.tag = 0
            action.showInView(self.view)
        } else {
            // iOS8:
            let alertController: UIAlertController = UIAlertController(title: "Change Map Type", message: nil, preferredStyle: UIAlertControllerStyle.ActionSheet)
            let cancelAction: UIAlertAction = UIAlertAction(title: "Back", style: UIAlertActionStyle.Cancel, handler: nil)
            let button1action: UIAlertAction = UIAlertAction(title: "Product Page", style: UIAlertActionStyle.Default, handler: { (action: UIAlertAction!) -> () in
                // doing something for "product page"
            })
            let button2action: UIAlertAction = UIAlertAction(title: "Video", style: UIAlertActionStyle.Default, handler: { (action: UIAlertAction!) -> () in
                // doing something for "video"
            })
            alertController.addAction(cancelAction)
            alertController.addAction(button1action)
            alertController.addAction(button2action)

            self.presentViewController(alertController, animated: true, completion: nil)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

}

正如我在iPhone上所说的那样，它可以工作，但是如果我单击iPad上的按钮，应用程序将崩溃，

2014-09-25 14：54：52.784 test [9541：1970048] 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UIAlertControllerStyleActionSheet样式的UIAlertController（）。
具有此样式的UIAlertController的modalPresentationStyle为UIModalPresentationPopover。您必须通过警报控制器的popoverPresentationController提供此弹出窗口的位置信息。您必须提供sourceView和sourceRect或barButtonItem。如果在显示警报控制器时不知道此信息，则可以在UIPopoverPresentationControllerDelegate方法-
prepareForPopoverPresentation中提供它。

第一个调用堆栈：（0 CoreFoundation 0x00613df6
exceptionPreprocess + 182 1 libobjc.A.dylib
0x01fdaa97 objc_exception_throw + 44 2的UIKit
0x0164da37 - [UIPopoverPresentationController
presentationTransitionWillBegin] + 3086 3的UIKit
0x00f54f75 __71- [UIPresentationController
_initViewHierarchyForPresentationSuperview：] _ block_invoke + 1666 4的UIKit
0x00f53554 __56- [UIPresentationController runTransitionForCurrentState]
_block_invoke + 226 5的UIKit
0x00f8721b __40 + [UIViewController _scheduleTransition：] _ block_invoke +
18 6 UIKit 0x00e4d62e afterCACommitHandlerblock_invoke + 15 7 UIKit
0x00e4d5d9 _applyBlockToCFArrayCopiedToStack + 415 8 UIKit
0x00e4d3ee _afterCACommitHandler + 545 9的CoreFoundation
0x00536fbe CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION +
30 10的CoreFoundation 0x00536f00 __CFRunLoopDoObservers + 400
11的CoreFoundation 0x0052c93a __CFRunLoopRun + 1226 12的CoreFoundation
0x0052c1ab CFRunLoopRunSpecific + 443 13的CoreFoundation
0x0052bfdb CFRunLoopRunInMode + 123个14 GraphicsServices
0x0438424f GSEventRunModal + 192个15 GraphicsServices
0x0438408c GSEventRun + 104 16的UIKit
0x00e23e16 UIApplicationMain + 1526 17测试
0x00085e9e top_level_code + 78 18测试
0x00085edb main + 43 19 libdyld.dylib
0x0273eac9开始+ 1 20 ???
0x00000001 0x0 +1）libc ++ abi.dylib：以类型为NSException的未捕获异常终止

可以在https://www.dropbox.com/s/54jqd8nsc67ll5g/test.zip?dl=0上找到该项目，以供下载并尝试。

Answer 1

错误消息告诉您，您需要给警报控制器popoverPresentationController一个位置，以便它可以正确定位自己。这很容易做-
只需检查是否有一个弹出窗口控制器并将发件人添加为源即可。

如果您的按钮是UIBarButtonItem：

if let popoverController = alertController.popoverPresentationController {
    popoverController.barButtonItem = sender
}
self.presentViewController(alertController, animated: true, completion: nil)

除此以外：

if let popoverController = alertController.popoverPresentationController {
    popoverController.sourceView = sender
    popoverController.sourceRect = sender.bounds
}
self.presentViewController(alertController, animated: true, completion: nil)