问题
The key UIKeyboardAnimationCurveUserInfoKey in the userInfo dictionary of a UIKeyboardWillShowNotification contains an Int with the value 7.
Now I need to pass this Int into UIView.setAnimationCurve(<here>). I tried to create the required UIViewAnimationCurve enum like this UIViewAnimationCurve(rawValue: 7). Because the raw value 7 is undocumented, the result is always nil.
It works fine this way in Objective-C. Any idea how to get this animation curve from the notification into a UIView animation using Swift?
Update: As pointed out by Martin, this is no longer a problem since Xcode 6.3.
From the Xcode 6.3 Release Notes:
Imported NS_ENUM types with undocumented values, such as UIViewAnimationCurve, can now be converted from their raw integer values using the init(rawValue:) initializer without being reset to nil. Code that used unsafeBitCast as a workaround for this issue can be written to use the raw value initializer.
回答1:
I think I figured it out, but I'm not sure if this is the way it's supposed to be done.
let animationCurve = unsafeBitCast(7, UIViewAnimationCurve.self)
UIView.setAnimationCurve(animationCurve)
Update: The solution contained in this question works as well.
var animationCurve = UIViewAnimationCurve.EaseInOut
NSNumber(integer: 7).getValue(&animationCurve)
来源：https://stackoverflow.com/questions/25168413/how-to-force-a-raw-value-of-7-into-a-uiviewanimationcurve-enum