Open Radar

 
Area:
UIKit

Summary:
According to the documentation for UIActivityItemSource ( https://developer.apple.com/reference/uikit/uiactivityitemsource/1620453-activityviewcontroller ), activity​View​Controller(_:​item​For​Activity​Type:​) can sometimes be called with a nil `activityType`. However, the declaration does not indicate it as being an optional value. This causes a compiler warning when checking if `activityType` is nil. However, if Swift compiler optimizations are turned on, the comparison to nil no longer happens which causes the app to crash.

Steps to Reproduce:
1. Implement `activity​View​Controller(_:​item​For​Activity​Type:​)` in a UIActivityItemSource as follows:

func activityViewController(_ activityViewController: UIActivityViewController, itemForActivityType activityType: UIActivityType) -> Any? {
  if activityType != nil {
    print(activityType.rawValue)
  } else {
    print("activityType was nil")
  }
}
2. Build and run with Swift compiler optimizations turned on



Expected Results:
"activityType was nil" is logged to the console when the activity view is invoked with a nil `activityType`

Actual Results:
App crashes when activity view is invoked with a nil `activityType`

Version:
iOS 10.2

Notes:
Because the documentation states that `activityType` can sometimes be nil, the UIActivityItemSource instance method declaration should accept `activityType` as an optional value like this:

func activityViewController(_ activityViewController: UIActivityViewController, itemForActivityType activityType: UIActivityType?) -> Any?

Configuration:
iPhone 6s