Workaround for EKParcipant URL accessing crash? - swift

Question

Some of my users have been sent me logs identifying a EXC_BREAKPOINT (SIGTRAP) Error on this line of code. I've been been trying to make it safe but all of the properties of EKParticipant are non optional so comparing to nil just gives me a warning saying it will always be true. If something is nil here how should I handle it?
Error Line
let participantEmail : String? = participant.url.absoluteString.lowercased().replacingOccurrences(of: "mailto:", with: "")
Apple Error Description
Trace Trap [EXC_BREAKPOINT // SIGTRAP]
Similar to an Abnormal Exit, this exception is intended to give an
attached debugger the chance to interrupt the process at a specific
point in its execution. You can trigger this exception from your own
code using the __builtin_trap() function. If no debugger is attached,
the process is terminated and a crash report is generated. Lower-level
libraries (e.g, libdispatch) will trap the process upon encountering a
fatal error. Additional information about the error can be found in
the Additional Diagnostic Information section of the crash report, or
in the device's console. Swift code will terminate with this exception
type if an unexpected condition is encountered at runtime such as:
a non-optional type with a nil value
a failed forced type conversion Look at the Backtraces to determine where the unexpected condition was encountered. Additional
information may have also been logged to the device's console. You
should modify the code at the crashing location to gracefully handle
the runtime failure. For example, use Optional Binding instead of
force unwrapping an optional."
Full Method
/**
Parses participants for a given event.
Goes through the EKEvents attendees array to build Attendee objects used to model a participant.
- parameter event: The calendar event we'll be finding the participants for.
- returns: An array of Attendee objects with the participants name, email, required/optional status and whether they've accepted their invitation to the event.
*/
private static func parseParticipantsIn(event: EKEvent) -> [Attendee] {
var participants = [Attendee]()
if let attendees = event.attendees, event.attendees?.isEmpty == false {
for participant in attendees {
let participantName : String? = parse(EKParticipantName: participant)
let participantEmail : String? = participant.url.absoluteString.lowercased().replacingOccurrences(of: "mailto:", with: "")
let isRequiredParticipant : Bool = participant.participantRole == EKParticipantRole.required
let hasAccepted : Bool = participant.participantStatus == EKParticipantStatus.accepted
guard (participantName != nil && participantEmail != nil)
else
{
log.error("Participant could not be parsed")
continue
}
let attendee = Attendee(name: participantName!, email: participantEmail!, required: isRequiredParticipant, hasAccepted: hasAccepted)
participants.append(attendee)
}
}
return participants
}

Answer 1

This appears to be a problem with the EKParticipant.url property. Any attempted access of EKParticipant.url causes a crash if you have a participant with the following email field within it.
"Bill Gates" <billgates#google.com>
I'd guess the quotation marks end the String prematurely. It is fine when accessed from EKParticipant.description so I intend to parse it from there.

Answer 2

This is a ridiculous issue, and Deco pinpointed it exactly. I used a different approach to get around it though: Since I'm already working in a mixed code base (obj-c and Swift), I created a class method on one of my obj-c classes that takes an EKParticipant and returns its URL as a string. Then, in Swift, I call that class method to get the URL instead of directly accessing the property (and crashing). It's hacky, but better than crashing and saved me from parsing the description.

Answer 3

This is rather old question but yet I hit this issue myself. My solution is to fallback to ObjC in order to workaround it.
Just add this ObjC functions to swift bridging header file and you are good to use them in swift.
static inline BOOL
participantHasNonNilURL (EKParticipant* _Nonnull participant) {
return participant.URL != nil;
}
static inline NSURL* _Nullable
participantURL(EKParticipant* _Nonnull participant) {
if (participant.URL != nil) {
return participant.URL;
}else {
return nil;
}
}
Example of usage:
extension EKParticipant {
var optionalURL: URL? {
return participantURL(self)
}
var hasURL: Bool {
return participantHasNonNilURL(self)
}
}

Answer 4

This is still an issue on macOS 11.2... I have reported it to Apple. I encourage anyone else hitting this issue to do the same.
The only Swift-only workaround that worked for me is:
extension EKParticipant {
public var safeURL: URL? {
perform(#selector(getter: EKParticipant.url))?.takeUnretainedValue() as? NSURL? as? URL
}
}

Answer 5

Validations are added incorrectly, please check the below response about how the guard could be used.
if let attendees = event.attendees, event.attendees?.isEmpty == false {
for participant in attendees {
guard let participantName : String? = parse(EKParticipantName: participant) else{
log.error("error in participant name")
return
}
guard let participantEmail : String? = participant.url.absoluteString.lowercased().replacingOccurrences(of: "mailto:", with: "") else{
log.error("error in participant email")
return
}
let isRequiredParticipant : Bool = participant.participantRole == EKParticipantRole.required
let hasAccepted : Bool = participant.participantStatus == EKParticipantStatus.accepted
/* guard validation is not required here */
if (participantName != nil && participantEmail != nil){
let attendee = Attendee(name: participantName!, email: participantEmail!, required: isRequiredParticipant, hasAccepted: hasAccepted)
participants.append(attendee)
}
}
}
return participants