UIAlertView crash on UIInputViewController

Question

I am working with Xcode 6.0 and swift. UIAlertView and UIAlertController (example:following 2 functions) work fine on myViewController inherited from UIViewController, but they crash on KeyboardViewController inherited from UIInputViewController. Doesn't Apple allow alertview on custom keyboard or is there any mistake in my coding? Any responses are welcome and appreciated.

func viewAlert() {
    var alertView = UIAlertView() <———
    alertView.addButtonWithTitle("Ok")
    alertView.title = "title"
    alertView.message = "message"
    alertView.show()
}    
func viewAlert0() {
    var alert = UIAlertController() <———
    alert.title = "title"
    alert.message = "are disabled in your device"
    alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))
    self.presentViewController(alert, animated: true, completion: nil)
}

 <——— debugger error point:

0x325ca19:  calll  0x327e620                 ; symbol stub for: pthread_kill
0x325ca1e:  movl   $0x2710, (%esp)
0x325ca25:  calll  0x327ec50                 ; symbol stub for: usleep$NOCANCEL
0x325ca2a:  movl   $0xffffffe7, -0xc(%ebp)
0x325ca31:  movl   %esi, 0x4(%esp)
0x325ca35:  movl   $0x0, 0x8(%esp)
0x325ca3d:  movl   $0x3, (%esp)
0x325ca44:  calll  0x327e476                 ; symbol stub for: sigprocmask
0x325ca49:  ud2    <====== Thread 1 :EXC_BAD_INSTRUCTION(code=EXC_i386_INVOP,subcode=0x0)

Answer 1

In ther hope it can help someone in Swift:

suppose You have a lib that must work with iOS AND extensions (in may case I use UIApplication.sharedApplication().keyWindow that is unavailable to extensions)

#if NS_EXTENSION_UNAVAILABLE_IOS


func captureScreen() -> UIImage {

    let window = UIApplication.sharedApplication().keyWindow
    let scale = UIScreen.mainScreen().scale

    UIGraphicsBeginImageContextWithOptions(window!.bounds.size, false, scale)

    window?.layer.renderInContext(UIGraphicsGetCurrentContext()!)
    let image : UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return image
}


#else
#endif

using #ifdef allow us to compile this file both for iOS and extension.

Answer 2

From iOS 8, we have new macro:

NS_EXTENSION_UNAVAILABLE_IOS

iOS doesn't permit to use some class in EXTENSION

iOS doesn't permit to use AlertView or AlertController if you are building an CUSTOM KEYBOARD EXTENSION

See more:

• https://developer.apple.com/library/ios/documentation/General/Conceptual/ExtensibilityPG/Keyboard.html
• https://developer.apple.com/library/ios/documentation/General/Conceptual/ExtensibilityPG/ExtensionCreation.html