iOS Swift convenience initializer self used before self.init called - ios

Question

so I have been trying to create a "Period" class, with the following attributes:
class PTPeriod {
// MARK: Stored Properties
var start: Date
var end: Date
var place: PTPlace?
//MARK: DESIGNATED NITIALIZER
init(start: Date, end: Date, place: PTPlace? = nil) {
self.start = start
self.end = end
self.place = place
}
And I want to initialize it with a convenience init that accepts a dictionary like the following:
{
"close" : {
"day" : 1,
"time" : "0000"
},
"open" : {
"day" : 0,
"time" : "0900"
}
}
This is my initializer, originally I put the heavy lifting into a helper method. However, i was getting the same error I have now so I removed the helper method and the error is still occurring. Unsure where it thinks I am calling self.
UPDATE: moved the date formatting into a date formatter extension, but the error still persists! unsure WHY. new init shown:
My new Convenience init:
// MARK: Convenience init for initializing periods pulled from Google Place API
convenience init?(placeData: [String:Any], place: PTPlace? = nil) throws {
var start: Date? = nil
var end: Date? = nil
var formatter = DateFormatter()
do {
for (key, value) in placeData {
let period = value as! [String: Any]
if (key == "open") {
start = try formatter.upcoming_date(with: period)
} else if (key == "close") {
end = try formatter.upcoming_date(with: period)
} else {
break
}
}
if (start != nil && end != nil) { self.init(start: start!, end: end!, place: place) }
else { print("we f'd up") }
}
catch { print(error.localizedDescription) }
}
Here is my DateFormatter.upcoming_date method:
func upcoming_date(with googlePlacePeriod: [String: Any]) throws -> Date? {
if let day = googlePlacePeriod["day"] as? Int {
if (day < 0) || (day > 6) { throw SerializationError.invalid("day", day) } // throw an error if day is not between 0-6
if let time = googlePlacePeriod["time"] as? String {
if time.characters.count != 4 { throw SerializationError.invalid("time", time) } // throw an error if time is not 4 char long
var upcoming_date: Date
let gregorian = Calendar(identifier: .gregorian)
let current_day_of_week = Date().getDayOfWeekInt()
let dayOfPeriod = day + 1
///TRUST THAT THIS WORKS... NO JODAS
var distance = dayOfPeriod - current_day_of_week // inverse = false
if (dayOfPeriod < current_day_of_week) {
switch distance {
case -1: distance = 6
case -2: distance = 5
case -3: distance = 4
case -4: distance = 3
case -5: distance = 2
case -6: distance = 1
default: break
}
}
/** time example: "1535" translates into 3:35PM
first two characters in string are "hour" (15)
last two characters in string are "minute(35)
**/
let hour = Int(time.substring(to: time.index(time.startIndex, offsetBy: 2)))!
let minute = Int(time.substring(from: time.index(time.endIndex, offsetBy: -2)))
upcoming_date = Date().fastForward(amount: distance, unit: "days", inverse: false)!
var components = gregorian.dateComponents([.year, .month, .day, .hour, .minute, .second], from: upcoming_date)
components.hour = hour
components.minute = minute
upcoming_date = gregorian.date(from: components)!
return upcoming_date
}
else { throw SerializationError.missing("time") }
}
else { throw SerializationError.missing("day") }
}

Answer 1

You have a failable initializer, so if it fails, you must return nil to let it know it failed:
if (start != nil && end != nil) {
self.init(start: start!, end: end!, place: place) }
} else {
print("we f'd up")
return nil
}
Also, in your do-catch, you need to either
re-throw the error in the catch block
catch {
print(error.localizedDescription)
throw error
}
eliminate the do-catch blocks altogether; or
just return nil:
catch {
print(error.localizedDescription)
return nil
}
If you do this, you'd presumably not define this failable initializer as one that throws because you're no longer throwing.
Given that you're unlikely to do anything meaningful with the thrown error, I'd just make it a failable initializer that doesn't throw:
convenience init?(placeData: [String: Any], place: PTPlace? = nil) {
var start: Date?
var end: Date?
let formatter = DateFormatter()
for (key, value) in placeData {
let period = value as! [String: Any]
if key == "open" {
start = try? formatter.upcoming_date(with: period)
} else if key == "close" {
end = try? formatter.upcoming_date(with: period)
} else {
break // I'm not sure why you're doing this; it seems extremely imprudent (esp since dictionaries are not ordered)
}
}
if let start = start, let end = end {
self.init(start: start, end: end, place: place)
} else {
print("either start or end were not found")
return nil
}
}