Why am I getting "fatal error: unexpectedly found nil while unwrapping an Optional value"?

Question

I am getting an error in Swift that I don't understand. Here is the code from my playground:

class Person : CustomStringConvertible
{

    let Name :String;
    let DoB :NSDate?

    init(name :String, dob :NSDate?)
    {
        Name = name;
        DoB = dob;
    }

    func age() -> Double {
        let now = NSDate();
        let age :Double = now.timeIntervalSinceDate(self.DoB!);

        return age;
    }

    var description : String {
        return "Name: \(Name), Age: \(self.age())";
    }

}

extension NSDate {
    static func dateFromComponents(year :Int, month :Int, day :Int) -> NSDate {
        let components = NSDateComponents();
        components.year = year;
        components.month = month;
        components.day = day;
        return components.date!;
    }
}

let helena = Person(name: "Helena", dob: NSDate.dateFromComponents(1986, month: 8, day: 10));
print(helena);

score 4 · Accepted Answer · edited May 23 '17 at 12:13

4

The documentation for the NSDateComponents date property:

Returns nil if the calendar property value of the receiver is nil or cannot convert the receiver into an NSDate object.

You have not set the date components' calendar, so .date is nil. Read the answers on this question for more about unwrapping optionals.

edited May 23 '17 at 12:13

Community

1
1

answered May 30 '16 at 16:27

jtbandes

115,675
35
233
266

William Kinaan · Answer 2 · 2016-05-30T16:57:08.747

1

Your problem is that

NSDate.dateFromComponents(1986, month: 8, day: 10)

returns nil.

You can solve that by creating a date object like this:

let format = NSDateFormatter()
format.dateFormat = "yyyy-MM-dd"
let date = format.dateFromString("1986-08-10")!

and then pass it like this:

let helena = Person(name: "Helena", dob: date);
print(helena);

Using NSCalender

let components = NSDateComponents()
components.year = 2000
components.month = 8
components.day = 1
let calender = NSCalendar(calendarIdentifier:  NSCalendarIdentifierISO8601)
let date2 = calender!.dateFromComponents(components)

let helena2 = Person(name: "Helena", dob: date2);

edited May 30 '16 at 16:57

answered May 30 '16 at 16:35

William Kinaan

28,059
20
85
118

2

NSDateComponents is a perfectly valid approach (cleaner than using a string), it just isn't being used properly. – jtbandes May 30 '16 at 16:50
@jtbandes totally agree ... updated using NSCalender – William Kinaan May 30 '16 at 16:56
1

OK, but are you still recommending that OP should use a string? Your answer doesn't explain why using NSCalendar is important. – jtbandes May 30 '16 at 16:56
@jtbandes no , the components are numbers – William Kinaan May 30 '16 at 16:57
@jtbandes the question is not about NSDate, it is about the nil exception. that'd be a different question – William Kinaan May 30 '16 at 16:58
The simplest solution in this case is to set the `calendar` property of `components` in the class method: `components.calendar = NSCalendar.currentCalendar()` – vadian May 30 '16 at 17:03

Why am I getting "fatal error: unexpectedly found nil while unwrapping an Optional value"?

2 Answers2

Using NSCalender